The first step to answering a specific thesis is to select a question, which you have done! Good. Your question is why are there so many unusual people in my family?
Next, a good thesis statement will do the following:
-Take a stance on which people can disagree
-Express ONE idea (not many)
-Provide your final conclusion
So, examples of a good thesis statement for your question could be:
My family has more unusual people than any other family.
My family has more unusual people than any other family I have ever met.
My family is more unsual than most families.
If you met my family, you would be astonished over how unusual they are.