Yes,rats indeed are alot more friendly and enjoy being handled if they have been handled from birth.The first 5 weeks of a rat's life is one of the most important times.This time is when they are learning about things,so the more you talk to them and handle them,the more friendly they are.
I handle my rats from birth and they grow up to be wonderful animals and enjoy being with humans.I start handling on the second day of their lives.
In the case with pet store rats,they are not handled often and thats why yours are probably skittish.However even then,with abit of work...they should come around.I rescued some rats before who were not used to handling,but after a few weeks...they warmed up.
Rats have different personalities tho.
But to answer your question,yes.They will be more handable if handled from day 1.
* Lisa *
* To the world you are ONE person,but to a rat you are the world *
* It's a rat thing...you wouldn't understand! *