Why are there so many left handed batsmen in cricket? Isn't this disproportionate to the general population.

"According to researchers, between 10 and 13% of the general population is left-handed. Yet if your experience of the world were limited to watching cricket(some of us can wish), then you would be forgiven for believing that the ratio is much higher. This is so because an examination of the top eight international teams reveals that left-handed batsmen are running at around 30% of those occupying positions 1-6 in the batting order." This article http://www.sportskeeda.com/cricket/right-isnt-always-right-why-batting-left-handed-is-better goes on to list the advantages a left-handed batsman has against the usual right-handed bowler, which then leads to a preference among teams to include them over right-handers, and also notes that some naturally right-handed players have deliberately switched, through practice, to batting left-handed: "When it is considered that batsmen like Brian Lara, Shivnarine Chanderpaul, Alastair Cook and Michael Hussey are all natural right-handers who bat left-handed, then coaches should contemplate encouraging their young right-handed charges to improve their chances of success by becoming southpaws."

This is not unique to cricket. As a Canadian, I know many naturally right-handed people (my own son included) who "shoot left" in ice hockey, which then carries over to them preferring to use left-handed golf clubs. -see icehockey.isport.com/icehockey-guides/determining-your-dominant-hand-in-hockey (webpage no longer exists)
https://www.prostockhockey.com/blog/hockey-stick-handedness/
https://blog.purehockey.com/hockey-drills-training-tips/how-to-determine-if-you-should-play-hockey-left-handed-or-right-handed/

"Scientists say that the left-handers' possession of right brain to left-side wiring gives them increased spatial awareness and the capacity to think and react quickly to objects in three dimensions. Skills, I am sure, that serve batsmen well when negotiating a cricket ball approaching them at high pace. Also, the fact that a batsman cannot be given out LBW - the third most common form of dismissal - once the ball lands outside the leg stump, provides a disproportionate benefit to left-handed batsmen. ... Furthermore, bowlers are not as comfortable, nor as proficient bowling left-handers."

http://www.theroar.com.au/2012/05/15/the-left-handed-advantage-in-cricket/

It is also a frequently-heard comment that having a right-left pair of batters who can change ends steadily disrupts the bowler's rhythm, so it is ideal to have at least two left-handers in the top 6 spots.

Cricket is far from the only sport where this effect can be noted. In tennis, Rafael Nadal is right handed, but plays left handed specifically because opponents face left-handers less often than right-handers, so there is an advantage (if you are good enough - I never was) in playing left-handed and getting different angles to your shots.