Well, but since it's in the German sentence, you should translate it. You don't need "mein" either.
However, in German, if you leave it out, I'd imagine it to sound grumpy (which isn't necessarily the case), which I guess doesn't happen in the same way in English. If it's supposed to sound loving and caring, I'd be sure to put the "mein" in.
It sounds like something a priest might say to a parishioner. "How might I help you my son." Aside from that, growing up my family used "my son" in a sort of tongue in cheek way to address their sons. Can't say I've ever heard "my daughter" used the same way. "My child," for a young girl, yes; "my daughter", not so much.