What causes people to be lefthanded?

Question

I can use both hands for diffrent things.

Answer 1

cause were smarter than you all.

Answer 2

I've read that babies tend to begin to show a preference (handedness) at around four months. My theory is that handedness could be related to "where" in development the baby's brain is at the time handedness gets fully established.

I believe there's a chance that the levels/combinations of brain chemicals/hormones present at any given time may influence which parts of the brain get developed more or less than others and at what rate each part of the brain gets developed. This could mean that regardless of when it is handedness gets established in a baby the chances are it is determined by parts of the brain that are more and less developed.

I can see, though, how genetics or prenatal influences (again, levels of brain chemicals/hormones influencing the development of the fetus' brain) could pre-program, to one extent or another, a leaning toward developing the side of the brain that favors either left-handedness, right-handedness, or a mix of both.

The above are, however, just my guesses. I reserve the right to be wrong, although I do think what I've said could point someone in the right direction with regard to further research.

Answer 3

I am right handed but my brother is ambidexter (both hands) because he was left handed at a time when it was not accepted and he was forced to use his right hand to write at school so now he can use both hands.
Left handed people are just the ones who were allowed to be that way because now it is acceptable.
25% of people are born left handed but only 8 to 15% of adults still are (more males than females).
It has to do with the right hemisphere of the brain being dominant and another theory about stress at birth (my brother was premature)

Answer 4

I read somewhere recently that babies who suck on the left thumb prebirth are left handed as adults and vice versa. I tend to think left handedness is genetic. My grandmother-mother-self-oldest daughter, all on my mother's side, are left handed and blue eyes too. Actually I'm ambidextrous because I got swatted by the teacher in first grade for using my left hand. After having a finger injury on the left hand a few years back and doing a strength test though, the doctor said I was definitely left handed.

Answer 5

Any combination of genetics, environment and social custom. The dominant side of your brain determines "handedness". This can be over ridden (to a greater or lesser extent, depending on the individual) by training a small child to use one hand in preference to the other. During my grandfathers youth left-handedness was still regarded as less desirable. He was taught to use his right hand, despite the fact that left handedness was his natural inclination. This resulted in his being ambidextrous (lit. either handed) My mother was left handed, my father right. Of five children 2 are "lefties", 2 are "righties" and 1 (me) is ambidextrous.

Answer 6

I guess the reason why some people are left handed like me is because we might see this in our parents who could be left handed as well. This could be genetics, one thing i know I'm left handed and I tried to learn with my right hand so now I use both of them. If you are left handed you should be lucky because we are very artistic and talented.

Answer 7

The latest word comes from a geneticist at the National Cancer Institute laboratory here who has been working for years with yeast and mutant mice and who has developed a novel theory that he believes will explain why 9 out of 10 people are right-handed, why left-handed parents are more likely to have left-handed children and why identical twins often have different handedness.

For more go to:
http://query.nytimes.com/gst/fullpage.html?res=9A01E1D6103BF935A25756C0A9669C8B63&sec=health&spon=&pagewanted=print

Answer 8

In animal kingdom, right vs left paw occurs 50-50.
In humans it is less as children are encouraged to be right handed.
Left handedness is genetic - that is if one side of the family is left handed - that genetic trait will be passed on. One reason perhaps that there aren't as many left handed people as right handed is that prior to our 'enlightened' times, south-pawed babies were put to death as being possess of the devil. Thus that genetic material isn't so common.
As it stands currently, left handedness like blue eyes is a recessive trait, so it takes a combination of parental with those traits in their lineage to produce a left handed child.
For example, my mother's father was left handed. She was right handed, her brother was left handed. Of my brothers and sisters, 2 brothers are left handed (as it seems to happen more often in males than females), one ambidextrous and all the girls are right handed.
As to what exactly causes it - genetics.

Answer 9

I've read that left handed people think more with their right brain, and right handed people think more with their left brain. The right brain influences dreams, creative aspects. The left brain is more on the intellectual level. Children were/are often traditionally trained to write with their right hand, even if they might actually be left handed. I believe I was supposed to be left handed, but my teacher in kindergarten made me write with my right hand.

Answer 10

I just saw a documentary on TWC yesterday that said all babies prefer one hand or the other and this choice is made while still in utero (before birth). It didn't say why but I thought it was an interesting fact.

Answer 11

Dominence of the right brain, simply. Some people develop their right brains more. Now you're right brain controls the left side of your body, which makes it so its easier to do tasks with the left side of your body.

If you listen to people in the middle ages, its because a demon was possessing them. So you should burn the southpaws.

An intresting fact. Lefties have the right side of the brain dominent, and thats the more creative side. Righties have the left side of the brain dominent, and thats the logical side.