Ungrateful?

Recently found out I’m pregnant, my boyfriend and I don’t live together yet and were in the process of looking for somewhere to rent before we found out, now that his parents know about the baby they want to buy us a house. We’ve been together for 2 and a half years but I feel like even with a baby on the way it’s just not right to let his parents buy us a house. I’m from a low income family (although I’ve grown up to make a fair amount of money at my job) whereas he is from a very well to do family who have a lot of spare cash, is it ungrateful of me to not want them to buy us a house? I’d really rather rent for a couple of years and then go about buying a house ourselves.