Father in law

Does anyone have a father in law who claims your child is all them. Everyone says my son looks like me he even said it when my husband showed him a pic of us side by side when I was a baby. But ever since my son was born he always says he’s a 100% (my husbands last name), he’s all (husbands last name). He hasn’t even met me or my son to know this. I find it really annoying because 1 why is it necessary to always say that and 2 he’s my son too so he can’t be 100% like y’all. Anyone else get annoyed with crap like that?