Erection and cause awareness in 4 yr old

I have a 4 yr old son. We have just started dealing with his tantrums ( as a normal 4 yr old). Also, he has a 5 month old brother (which we think might have led to increased tantrums). His dad is posted abroad for months at a time tho' we talk daily n have skype weekends. Hence I am basically functioning as a single parent and at times vent my frustration on him :(. Recently he has told me that his penis gets stiff when he watched a girl with scant clothes in a magazine and when he likes someone like a drenched girl in a song. Is this kind of erection awareness and linking it to the cause, normal for a 4 yr old? I have told him it was normal, part of growing up but not to speak abt it to anyone other than mom or dad. but we were freaking out. please let me know if its normal at this age??

[Kevin Kennedy, Ph.D.]

There's no need to 'freak out', as you say. It is fine. It's also important to refrain from venting your frustration on him. The fact that you are in the position of being essentially a single parent does bring about certain stress, that's for sure, but it does not justify your managing your emotions poorly.