How many kids is "too many"?

How many do you think is too many? I ask because I know someone in NC that has just had her 7th. They are all home schooled and never leave the house other than to go to church. All of the children are extremely rude to anyone else as they haven't learnt proper social skills. Also, the mum had them on a buddy system - she just looks after the baby, but then he rest pair up to look after themselves. To me, if you can't look after that many, don't have that many.