I was born, raised and lived in the UK for the first 30 years of my life. My two daughters from my first marriage (both born in Canada)are entitled to British passports, but my son (also born in Canada)from my second wife is not, because his mum and I were not 'married' when he was born. His birth certificate bears my family name, me as father, etc. I brought this up with the passport folks, first in Vancouver (they couldn't believe it) then in Ottawa (they couldn't believe it) then in Liverpool (they could believe it and said it was one of those things that was grossly unfair and outdated but is difficult to get out of the system because it is dependent on other clauses, blah, blah, blah) They told me I could fix it by one of two means: apply to the British embassy in Ottawa to have him officially 'registered' or marry his mother (I did). They now seem uncertain as to whether I need to adopt my own son to make it legitimate.