I read his biography and he said he was just selfish. He loved to travel. In fact he turned down Roman Holiday because he wanted to spend some time in Europe rather than do another film.
And judging by how some of my work colleagues look so emotionally drained from having kids it seems like a good idea to follow his lead. (Also what if my child has Asperger's too?! Its a cruel punishment to bestow on someone, albeit without meaning to).