Statistics, Correlation and Kids behavior

I wanted to touch base upon a point from Freakonomics.

Was listening to the radio the other day, driving from work. Heard that a study has discovered that there was a high correlation between waking up early in the morning and getting good grades.
This was concluded by saying, early birds achieve good grades. Sounds logical right..!!

But after reading Freakonomics, there is an other way of looking at it.
When you are speaking of correlation, consider this statistic about the cities with most number of cops had the highest crime rate i.e; Washington DC and Denver. If we conclude it by saying that cops are causing all that crime, we've certainly goofed up.
Consider this tale about a Czar who found out that the most people died in the cities with the most doctors and decided to shoot all the doctors to increase the mortality rate.

By now you must have understood the folly in the correlation between early birds and their grades.
Speaking of correlation:
When we see a correlation between X and Y, it could be one of three possibilities:
X causes Y, Y causes X or X and Y are caused by an external factor Z.

So the reason for the higher grades could be any of three possibilities:

1. The students who get up early in the morning to study, get more time to study (X causes Y).
   
2. Actually, the students who are interested in studies tend to get up early in the morning. Obviously these students who are interested in studies are going to have good grades (Y causes X). It could be foolish to wake your son up early in the morning, just expecting his grades to catapult upwards.
   
3. It could be their genes. Studies have shown that a child inherits 50% of his IQ from his parents. (Didn't say which parent, so I am assuming that both the parents are well educated.) So most of the time, the parents may be early birds themselves, which the child eventually imbibes. (External factor Z causes both X and Y)

Digressing here a bit.
It is interesting to read more about how much do parents really affect their kids. Studies show that 50% of the behavior is in the genes itself. Interesting to note a study of the children who were adopted into well educated families. The study found out that the IQ level of the adopted kids was most similar to the IQ level of their biological parents than their adopted parents.

I always wanted to find out a solution to what makes some kids enamor books while others don't. Heard from my sister that a lot of parents read books to their kids at a young age, which helps the kids form a fascination. Believed I had an answer.

Was speaking to my CEO the other day. He has read books for all his kids, while they were growing up. But only 2 of the 5 kids have enamored books. He thinks that it's more in the kid's personality. Its not easy to change that.
Hmmm.... wanna do more research on this, will update you