When do you know know whether baby is right or left-handed?

[Xiaou2]

 When I was in first grade..  I recall them passing out scissors.  They asked
me if I was a lefty or a righty.    I never paid attention, I guess, so didnt know.

 I think I was equally good with either hand.  Maybe completely ambidextrous.
(though, equally horrid in both hands   )

 After that time, I think I decided to use only one side... which was left.  However,
while I write with my left...  I still do many things with the right, Such as throwing
a baseball.   
 
 At age 20... I finally got to take KungFu lessons.  In this style,  called "Wing Chun",
(a chinese close range combat art)  I was taught the importance of being
equally skilled, accurate, and strong... with both sides.   (If you are weak on
one side... people will see that, and intentionally take advantage of it.   Thus
making you only as good as your worst attribute)

 While I can not write with both hands well...  I can now punch or kick equally fast, accurate, and strong with either side.  The training in that system is very critical, different, and specialized... and leads to amazing results in a very short timeframe.


 Finally,  there are many others around the world who have trained themselves
to use either hand.. or both at the same exact time.   Or even to use their feet
to do many skilled things.   Some out of necessity, and some out of desire.

 I believe the main reason why we may choose one hand of the other.. is mostly
because we dont have the time or discipline to develop both equally.   

 In martial arts.. I found that if I was really kick --I'm attempting to get by the auto-censor and should be beaten after I re-read the rules--  with a certain kick on
one side... I would then show others that side.  This making it ever better... 
which made it disappointing to even use the 'bad' side.   I had to
fight myself to use my weaker side much more than the good side...
until it was as polished as the previous good side.

 Many kids are the same way.   When they use one hand more than the
other... it gets stronger and more accurate.  So,  they will unconsciously
decide to use that better side.   One day, they will realize it, and proudly
proclaim mastery of that side..  and mock all others who use the "Other"
side         hehe