names

I'm starting to get why everyone says to hold off as long as possible before telling everyone your future child's name.  We decided to name our kid Liam.  Luckily, everyone we've told says they really like the name, and think it's cute.  On the other hand though, the majority of people we tell ask if it's a family name.  That just confuses me.  It's a fairly popular and cute kid's name.  Why would people automatically assume it's a family name?  Do they think that Jeff and I are just that uncreative with names?  Also, anyone over the age of 65 that hears the name Liam gets confused.  Apparently the name became well known right after that age group all stopped having kids.  My grandma especially gets confused by the name.
Grandma: "lee-UM?  Is that like Ian?"
Me:  "Uh, no.  It's like Liam."