To my knowledge, the people that I mentioned who sucked their thumb are not mentally challenged, though they were slow in school. Note, they are women, though that is irrelevant. In regards to your case, I'm wondering if the woman you mentioned is normal or suffers some mental disability.Pardon me if this is not directly related. I just want to know your opinion about an acquaintance named Tintin. She is around 30 years old, married and with one child, a toddler. She speaks in a normal. But I have noticed that when her mother is present, her diction changes to that of a little girl. Even her pronunciation of some words become like mimicking a girl. When a friend called her attention to that issue, she said that she just got used to that kind of speech when talking to her mother because she grew up that way. What do you think is the problem with Tintin?