Both Daniel and Eleanor seem to have inherited the same problem. They were both the last in their class to lose their first tooth, and they've both held on to their milk teeth for longer than normal.
A couple of weeks ago, we had to take Eleanor to see an orthodontist as she has still got her canine milk teeth, the fangs I call them, and the dentist couldn't feel one of the second teeth in her gums. The orthodontist took x rays and discovered that both the second teeth were there, but one still had quite a way to come down. It was decided that they would remove the first teeth to make way for, and help, the second teeth to descend.