But he does have family.
Turing had an older brother and his brother does have direct descendants. One of them wrote the following note to me:
After reading about your petition on the BBC website, I thought you'd like to know that there are members of Alan Turing's family around (although not direct descendents for obvious reasons!). He was my mother's uncle. Most of the family have not retained the name due to marriage, but my step-uncle is a Turing. My family have always remembered Alan Turing proudly.
Other people wrote to say that they know of other family members. So if Gordon Brown does decide on offering an apology there are family members who could decide to accept (or reject) it.