"My toddler has a relatively new habit of sticking his hand in his diaper and often playing with his penis. I don't want to tell him not to touch but I do wish he'd do it less. One forum I read suggested it's a sign of autism, but I'm not sure how or why. Is this normal? And should I just ignore it?"
First, rule out any medical issues like a dermatological condition, fungal infection or other illness. Look for obvious outward symptoms such as pain, problems urinating, flaky skin in the area, redness, swelling, bleeding or skin discoloration that wasn't there before. If any of those symptoms are present then see your health care provider immediately. This alone could resolve the issue.
Barring any medical problems, however, I would say that this is completely normal behavior not to worry about. There could still be some underlying issues, though. Since you are sending me this in July, I'm wondering if you have noticed it since summer started?
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