There is absolutely no reason to check your son's IQ. Being left-handed is not a mental problem. About 10 to 15% of all people are born with a preference for the use of the left hand. If you force him to use the right hand, he will be slower to catch up with writing and may have speech problems too. Some parents force the child to be right-handed and such children also grow up to do well in life. There are no specific rules for anything, although there are basic principles:
1. Be affectionate and express you affection at suitable times.
2. Have clear and simple rules and be consistent.
3. Your child is a person, with his own strengths and interests. Respect them, as long as they are not harmful to anyone.
4. Your child is not born only to achieve the goals you have in mind, but to enjoy being with you and to grow up happy.