Like Father, Like Son

I find it interesting that children are born with certain tendencies.  Some of my children sucked their thumbs when they were little.  Some didn't.  Only one sucked his fingers and his son now does the same thing.  I wonder if that tendency is hereditary or not.  Another son sucked his thumb and his daughter sucks hers.  My twins didn't suck anything and their children don't either.  The one who is breaking the trend is my youngest.  He sucked his thumb but his daughter sucks a pacifier.  Food for thought:)