In particular, much has been made of the apparently statistically significant preponderance of left-handers among recent Presidents of the United States, so it may be worthwhile to consider the subject in some detail.
Over the last 30 years, three or four of the last five US Presidents have been left-handed: Barack Obama, Bill Clinton, George H.W. Bush and possibly Ronald Reagan, with George W. Bush being the only clear right-hander during this period. Reagan is often described as ambidextrous rather than left-handed, or possibly a natural left-hander who was forced to switch to right-handedness as a child, although there actually appears to be no documentary evidence for this switch, and perhaps no real reason to consider him anything other than a right-hander. In the 2008 election, both main candidates (Barack Obama and John McCain) were left-handed, and in the 1992 election all three main candidates (George H.W. Bush, Bill Clinton and Ross Perot) were.
Looking further back, seven of the last fourteen Presidents have been left-handers or ambidextrous (including, in addition to the four noted above, Gerald Ford, Harry S. Truman and Herbert Hoover) which, although less startling, still appears highly significant. Hoover and Truman, however, although usually considered left-handers, both wrote with their right hands. Before Herbert Hoover in 1929, the handedness of US Presidents is difficult to establish with any certainty, and during the 18th and 19th Century left-handedness was considered tantamount to a disability and so was often suppressed from a young age. There is therefore no reliable way to extrapolate the statistics back further. Overall, to the best of our knowledge, 6 or 7 out of 42 US Presidents since Independence have been left-handed (about 14% or 17%, as compared to 10-12% in the general population). If we also include vice-presidents, the statistics reveal a rather unremarkable 7 out of 76 left-handers (about 9%).
While clearly statistically significant compared to an incidence of left-handedness of around 10% in the population at large, many have written off the phenomenon of recent US Presidents as mere coincidence, which is still a plausible response. Others have put it down to the fact that Presidents often move into politics from career areas that left-handers are attracted to, especially lawyers, a hypothesis which remains unproven and unconvincing. Still others, though, have tried to explain it as due to the extra mental resilience required for left-handers to succeed in a right-handed world, or due to the increased ability of left-handers to process language in both hemispheres of the brain leading to enhanced communication skills, bare assertions largely devoid of any scientific justication.
It is interesting to note, by way of comparison, that just two out of the fourteen British Prime Ministers in the Post-War period have been left-handers (Winston Churchill, although often claimed by the leftie camp, was actually not), and every Canadian Prime Minister since at least 1980 (seven out of seven) has been right-handed. So, it is perhaps inadvisable to attach too much significance to the American experience.
Just in passing, the use of "left wing" and "right wing" in a political context has no particular semantic significance, but owes its existence to something as mundane as the layout of the short-lived National Assembly of revolutionary France in 1789, where the conservative nobility was seated on the right hand side of the presiding official, and the radicals of the Third Estate to his left. Although the seating arrangements actually changed over the years, the associations of right with conservatism and left with radicalism and socialism persisted in France, and was gradually adopted by other countries.
Quite why the French nobles decided to sit on the right is not known, however. It is possible that they chose the right-hand side in the belief that it was the superior or prestigious side (a belief common in many ancient cultures, and strongly endorsed by the dominant Christian religion), or it could have been entirely arbitrary and random.