A short article in the current (February 2011) BBC History Magazine suggests that a medical condition affecting Henry may have been responsible for his inability to produce male heirs. This is taken from an article in The Historical Journal, vol 53, no 4, CUP, by Caterina Banks Whitely and Kyra Kramer. Henry may have been "positive for the Kell blood group". The unborn children of fathers with this trait are apparently likely to be attacked by the mother's antibodies. This would explain the number of miscarriages and stillbirths suffered by Henry's first two wives. The condition does not affect all children in the womb, so Mary, Elizabeth and Edward survived. It is also possible that Henry suffered from McLeod syndrome (affecting Kell positive individuals) which can later lead to certain psychological symptoms including depression, paranoia and "unexpected" behaviour. This problem tends to show itself in the 30s and 40s.
Susannah Lipscomb, in her excellent book about Henry's later years, reminds us that something certainly set off anger, suspicion and tyrannical behaviour after 1536. Given Henry's formerly devout adherence to Rome, expressed especially in his rebuff of Luther's sacramental theology, and his search for a theological answer to his desires for both a male heir and Anne Boleyn, it is surely right to ask just how much the establishment of the Church of England owes to his medical (and psychological?) condition at the time. Is this an unfair question? I do not ask it to be disrespectful, but it is not the only question to be asked about the English Reformation.The above image of Henry is taken from this interesting article about a mural discovered in a private house