The one who said his firstborn is his favourite. 
He needs a brain rinse. His second born will feel crap when he's old enough to find out. Even if the dad protests that he was stupid it won't turn the clock back.
We all worry after our first, that consecutive dcs won't be loved as much. But we do love them just as much, sometimes differently. We may not always like some of dcs behaviour but they're our dcs and we stick by them. Even if someone did favour one to blog about it is ridiculous.
I despair at society today. And the internet is blamed for a lot of silly adults sharing their pathetic thoughts. But is it? They choose to do this. I've been guilty of writing crap on here but I'd never say something so damaging about my own dcs. He could've come on mums/dadsnet or similar and done it secretly?