My 20yo cousin and his 17yo girlfriend are expecting a baby. It was a shock and they are blaming the girl's Mum because the Mum told her daughter to stop having the contraceptive injection as she's gaining weight. So cousin's DP stopped taking it and they were using no alternative contraception.
Tbh I wouldn't be that bothered by the pair of them saying it as they are both very naive and the girlfriend is very much under her mother's thumb.
However they've told this story to the entirety of my very big family and not one member of my family are saying "Well actually, you should've stuck something on the end of it!", every family member is saying "Oh it's not their fault, her Mum told her to stop taking the injection so it's her fault."
When I pointed out that actually, they should both have been a bit more responsible every person I said this too got annoyed at me and told me not to say the same to my cousin as it's not his fault 
WIBU to shout at them all next time that actually no, the girlfriend should have taken some responsibility for her own contraceptive methods and my cousin should have taken some responsibility for his contraceptive methods and now that there is a baby coming they should stop pointing the finger at her Mum and start getting ready for it's arrival?