There are many signs that can possible point to you being smarter than the average person … But these?  Just plain weird:
1. You’re the oldest child. A study in 2007 found the oldest child in a family tends to have a slightly higher I.Q. . . . about three points, on average.

2. You don’t smoke. A study in 2010 found that smokers between 18 and 21 had an average I.Q. of 94 . . . while the average non-smoker’s I.Q. was 101. And people who smoked more than a pack a day had an average I.Q. of just 90.

3. You have a cat. A study last year found that dog people tend to be more outgoing. But cat people tend to be smarter.

4. Your mom breast-fed you. Two recent studies found that kids who were breast-fed had I.Q.’s that were seven points higher than kids who weren’t.

5. You’re tall. This one’s controversial, because obviously there are plenty of short people out there who are smart . . . and plenty of tall morons. But a 2008 study at Princeton found that taller kids tend to do better on cognitive tests.

http://www.businessinsider.com/signs-youre-smarter-than-average-2015-2?op=1