Thomas Boleyn and Elizabeth Howard married around 1498 or 1499. Ives says that Elizabeth's jointure was settled on her in 1501, and jointure was usually settled within about a year of the marriage, though there was no exact time limit.
They had at least five children, but only three lived to adulthood. Thomas once wrote,
When I married I had only 50£ a year to live on for me and my wife as long as my father lived, and yet she brought me every year a child.
Mary is thought to have been born around 1500, and was probably the eldest surviving daughter. George is believed to have been born in 1503 or 1504. The graves of two other children, Henry and Thomas, are extant, but their birth years are unknown.
Two birthdates are suggested for Anne: 1501 or 1507, with many scholars favoring the former. I believe the 1507 birth date to be the correct one, though I'm in the minority.
Two key pieces of evidence support a birth date of 1507. The first is a biography of Queen Elizabeth, written by William Camden. Camden had been put to the task by William Burghley, Elizabeth's secretary. Camden was given access to both Burghley's papers and the state archives - some of which are no longer extant, thanks in part to the 1731 Cottonian Library fire.
Camden wrote in his book, The Annales or Historie of the Most Renowned and Victorious Princeffe Elizabeth that Elizabeth's mother had been born in 1507. Some have suggested that later scholars simply mistook the last digit for a seven when it was actually a one, but Camden wrote the number in Roman numerals.
Camden stated that Henry fell in love with Anne when she was twenty-two years old (some transcriptions say twenty). This is understandable given the lack of documentation of the beginning of Henry and Anne's affair. In any case, Camden reiterates that Anne was in her early twenties, not late twenties, when Henry sought to marry her. Despite Anne's matrimonial difficulties, it seems unlikely the attractive daughter of a wealthy, highly-placed courtier like Thomas Boleyn would be unwed in her late twenties when Henry fell in love with her around 1526.
The second piece of evidence comes from the Duchess of Feria, Jane Dormer. Dormer was a friend of Queen Mary I. Her autobiography contained a section on Anne Boleyn. Dormer was biased in favor of Mary, and her biography of Anne contained several errors, but she stated that Anne had gone to the scaffold before her twenty-ninth birthday. It's a very specific number that happens to coincide perfectly with Camden's birth date of 1507. Dormer likely got this information from Mary herself, and had no reason to lie or invent this number, since it probably would have made Anne less sympathetic if she were older.
In 1514, Anne was sent to the court of Archduchess Margaret of Austria. This arrangement seems to have been a personal favor from the Archduchess to Thomas Boleyn, who was serving as ambassador. The two had developed a warm relationship, and Margaret agreed to accept Anne into her court. Traditionally, a maid of honor had to be at least twelve years old to serve at a royal court, and this is used as an argument to support the earlier birth date. However, researcher Garreth Russell has noted that there was another English girl at the court at that time who was born in 1506.
The Archduchess commented on Anne:
I find her so bright and pleasant for her young age that I am more beholden to you for sending her to me than you are to me.
It seems odd that the Archduchess would comment on Anne's youth if she was the ordinary age for a maid of honor. Anne was also known as "la petite Boulaine" while at court. This could, of course, refer to her small stature, but it seems more likely to have referred to her age.
While at court, Anne wrote Thomas a letter which is also used to support her being in her teenage years at the time of its composition, but education in the Tudor era was different than it is today. It started earlier and was far more rigorous. In it, Anne asks him to pardon her mistakes because the letter is the first she has composed by herself, something unlikely to have been written by a fourteen girl. (In comparison, her daughter, Elizabeth, was writing flawless letters in Italian by age ten, and knew several other languages.)
Anne's handwriting looks elegant and well-formed, but the French is terrible and in some places, the words are illegible. Other samples of handwriting of Tudor children show that the letter was not beyond the capabilities of a seven year old girl, especially one as intelligent as Anne. Her handwriting was quite improved in her later letters.
Anne returned to the English court in early 1522 because her father was trying to arrange a marriage for her to James Butler. The marriage never happened, possibly because Anne had become entangled with Henry Percy.
Most of our narrative of the Percy affair comes from the memoirs of George Cavendish. He refers to Anne as being "very young" when she was sent to France - would he have made such a remark if she was the ordinary age of twelve or thirteen when sent abroad? Wolsey calls Anne a "foolish girl" when he breaks up her romance with Percy, a term more suited for a teenager than for a woman of twenty-one, as she would have been if she'd been born at the earlier date.
George Wyatt refers to Anne as "fresh and young" when she first came to court in his written version of his grandfather Thomas Wyatt's memoirs. Simon Grynée wrote of her in 1531 that she was "young, good-looking, of a rather dark complexion, and likely enough to have children." Again and again, the descriptions emphasise Anne Boleyn's youth.
William Forest, a Catholic poet who penned odes to Katharine of Aragon, wrote of Anne:
At time of canvasinge this matter so,
In the courte (newe entred) theare dyd frequent
A fresche young damoysell, that cowld trippe and go,
Forest was actually present for some of the hearings on Henry's divorce, and so may have seen Anne himself to describe her.
The king didn't notice Anne until late 1525 or early 1526. If Anne had been born in 1501, she would be an "old maid" by the standards of the day. But no one mentioned this when decrying the king's relationship with her. They threw everything but the kitchen sink at Anne Boleyn, criticizing every aspect of her person and her background, but no one mentioned her age in protesting she was not a suitable queen.
In 1529, Anne Boleyn was quoted by Chapuys as complaining to the king
I have been waiting long, and might in the meantime have contracted some advantageous marriage, out of which I might have had issue, which is the greatest consolation in the world; but alas! Farewell to my time and youth spent to no purpose at all.
If Anne was twenty-eight when she had this conversation with the king, her "youth" had already since passed her by, according to the standards of the day. The statement makes more sense if she was only twenty-two, watching the years of her youth and most fecund time pass by while waiting to be married. Many women of her class married in their early twenties, as had the women in her family. And Anne was still waiting for the king to pry his way out of his marriage to Katharine, with no end in sight.
By the time she and the king married in 1532, Anne would have been nearing what was considered a dangerous age for a first pregnancy if she was born in 1501. But again, no one mentioned this when the king had Gardiner brag about her "aptness to procreate children," and he used the same phrasing in 1533 when writing to the German princes to announce his marriage.
Up to just a few days before Anne was arrested, Henry was stressing her apparent fertility. Despite what he supposedly said to Anne while she lay in her bed, recovering from a miscarriage, it doesn't appear her "aptness to procreate children" was in question.
When Kateryn Parr experienced her first pregnancy at the age of thirty-five, she received numerous worried letters from her friends and family. Her cousin, Nicholas Throckmorton, referred to her as "past middle age." Their fears ended up being justified, because Kateryn did, in fact, die shortly after giving birth. If Anne Boleyn was born in 1501, she would have been thirty-two when her daughter, Elizabeth, was born, but no one mentioned her advanced age for bearing her first child.
If Anne climbed the scaffold steps at age thirty-five in 1536, she would have been nearing the end of what the Tudors considered her fertile years. Just like Katharine of Aragon, Henry would have been ridding himself of a wife who couldn't give him children. If she was only twenty-eight, then she had plenty of fertile years left and the perspective changes.
If Anne was born in 1507, she was - ironically enough - around the same age as the woman who would replace her, Jane Seymour. Chapuys noted Jane's age in a letter with a snide insinuation about how long she'd lived at court when it became apparent she was Henry's new choice as queen. In his view, a woman who'd been so long "on the shelf" and at court was likely not a virgin. Despite all the mud he threw at Anne Boleyn, this was one slur he never cast in her direction.
When St. Peter-ad-Vincula was excavated in the reign of Queen Victoria, efforts were made to identify the remains of the famous persons buried beneath the floor around the altar of the tiny chapel. This task was complicated by the fact the chapel had been used as a parish church, and other burials had occurred beneath its floor. The spot Anne Boleyn was supposed to rest was occupied by the lead coffin of a woman who had died in 1750, and Anne's bones had been unceremoniously pushed aside to make room.
The doctor who examined the bones identified them as being Anne Boleyn based on the graceful characteristics of the skeleton.
The pavement was then lifted on the spot which was marked on the plan as the place of Queen Anne Boleyn's interment, and the earth removed to a depth of two feet; it had certainly not been disturbed for upwards of a hundred years.
At this depth the bones of a female were found, not lying in the original order, but which had evidently for some reason or other been heaped together into a smaller space: all these bones were examined by Dr. Mouat, who at once pronounced them to be those of a female of between twenty- five and thirty years of age [...].
If the bones were really Anne's, it would possibly lend support to the 1507 birthdate. However, we cannot say for certain they were hers, nor that the doctor was able to accurately judge the age of the person to whom they belonged.
As with many details of Anne Boleyn's life, it seems this one will always remain a subject of debate.