Countries With the Highest Percentage of Male Population World Bank (like below)

[Irish_Dem]

1. We can take a guess at some of the reasons.

And some of the consequences.

For example China's One Child Policy resulted in a severe bride/female shortage.
So now China has to kidnap women from nearby countries for their wife/sex trafficking rings.

If the Chinese were only allowed one child they chose to keep a male
child and discarded or killed the female babies. This has caused a lot of problems.
There are not enough women in the country for the men to have wives.
The farmers need wives to help run the farms and provide labor.

Also the Chinese kept the boy children because they thought they would
provide better for them than girls. They are finding out the boys have abandoned
their parents and the daughters look after them better. China had to enact a law
that children had to visit their parents so many times a year.