How and why does hip dysplasia happen? In my family, three different cousins had children with it. Before that, I didn't know anyone who had a child with that problem.

Hip dysplasia is a condition where the hip doesn't form properly. The problem can be mild, where the ball part of the hip joint doesn't quite fit into the socket or it the joint can be completely out. One hip can be affected or both can be.

For some reason, hip dysplasia does happen more often in girls than boys and often it is the first child who is affected. Children who are born in the breech position (feet first) are at higher risk of hip dyplasia as well.

Doctors have found that the problem does also run in families. This doesn't mean that if you have a child with hip dysplasia, your child will too, but that some families - such as yours perhaps - have a higher rate of hip dysplasia than other families.