GET A LAWYER!!!!! You can lose to the better lawyer.  It happened to me only I lost my son to strangers..........

I think the only way he can get custody of your son is , if he can prove that you are an unfit mother. If you are concerned., get a lawyer that the state will provide you free of charge, if you cant afford one of your own.

where i live i have seen kids taken away from parents for just slapping them.  i have seen parents really have to fight to get their kids back.  don't slap or leave young one's unattended while you go to the store.  i have seen that too.

Are you gang related . Crips, Bloods. Tango. Mexican Mafia. AC AB. . That would do it.

abuse , neglect , or failing to provide the neccessaties of life ..  get a lawyer, better safe than sorry

As long as your child is in a stable loving environment,his needs must be met,he should not be subjected to an alcoholic or drug taking parent/s,he should not be around any form of violence within the home nor should he witness any domestic abuse,also he must attend school every day.If you can prove that this is what you provide for your son,you should not have a problem. 

if you are providind a good decent home for your son I don't think you have too much to be concerned about.His father may win joint custody (Weekends,holidays etc.) but it's not usual for a working father to gain full custody when a good home & upbringing is already being provided by the parent currently with custody.