Dad's can do hair too! Does she look upset? No, she seems to be enjoying it AND she's not getting a brush yanked through her hair.
Moms, how would you deal with this?
It's important for parents to understand the importance of the balance that grows from a child's relationship with his/her father AND mother. Many Moms would FREAK by seeing this, but it's important to know, it's not wrong for THEM just because you don't like it...plus, it's likely to happen behind your back anyway. My suggestion: instead of "freaking out," leave the room and pretend you didn't just see this. This could be a very endearing event for both of them that could sustain their relationship for many years! If you try to control it, you are interfering with their relationship.
Mary Bowles, MA, LMFT, RRT, MIAAN