What's the wait ?

So my boyfriend and I have known each other for years, and his family and my family have known each others for years. A couple of months after dating  I've moved in with him , and he's been staying with his parents house. He's 29 ( I know it sounds like an irresponsible grown ass man) 
But is parents have a huge house, and they're very family oriented. Which is exactly why, since we've found out I was pregnant, I've been asking him to tell his family . I'm now 10 weeks pregnant and he still hasn't told them. 
It's his second child. His first is 8 years old. 
I've had multiple conversations with him about telling them, but we end up arguing every time. 
He says "I just don't want to tell them yet" 
And when I ask him why, he says he doesn't have any reasoning behind it, and he's not hiding it, but he "just doesn't want to tell them" 
I tell him I feel as though he's hiding the pregnancy but he denies it , and gets upset that I would think that . So at this point I don't know what to do or what to think .