Which thing decides that you're left handed or right handed?

Genetics.

Dexterity, strength, and control.

Most children quickly start to learn which side they favor. They naturally start grabbing things with a particular hand. Some people are closer to ambidextrous than others and it might be confusing when they are very young.

My mom is lefty, but she cooks with her right. Stirs pots that sort of thing like a righty. I’m righty, but I naturally turn left and cartwheel left with much more stability.

I watched a documentary, and handedness came from which thumb that a fetus sucked on before birth decided which hand was dominant.

I’m a lefty.

I’m certain I was born right handed.

I am left handed. I write with my left hand and throw a ball left handed. I am also left eye dominant so I look through a telescope with my left eye and shoot left handed.
But, I use musical instruments and technology right handed since that is the de facto standard. I have no problem with it.

Back in kindergarten I started to write on the blackboard with 2 pieces of chalk , one in each hand. I would make an “t” by making the down stroke with one hand and the cross stroke with the other. I clearly remember my teacher telling me I needed to write with one piece. and asking me which hand I preferred. I picked my left.

I’m a bit different when it comes to this because I write right handed, I would say I right handed. But I throw AND catch left handed and my left arm seems to be stronger than my right. I can do some things equally well with both hands.

It’s how you’re born!!! My cousin was born left handed back when it was thought that using the left hand predominantly meant you were possessed by the devil. My aunt was determined to make him right handed. She made him take things in his right hand & whenever she saw him using his left hand, she’d force him to switch it to the right hand. He’s now 60 years old; & he is left handed as even with ALL her efforts, she couldn’t change how he was born.

I was born right handed. When I had my stroke, I lost the use of the left side of my body. The doctors said the stroke had been on the right side of my brain & that the right side of the brain controls the left side of the body & the left side of the brain controls the right side. So, technically speaking, your brain controls which side is your dominant side.

While in high school, I had an injury to my right hand where I couldn’t hold a pencil or pen so I couldn’t write. It took a while, but I did train my left hand how to write when needed. Still, once my right hand healed, my dominant side took back over & I no longer fell back on the left hand for writing!!!

My Grandmother was ambidextrous & she had NO dominant side. She did things equally well with her right & left hand. Now that you’ve asked the Q, I’m wondering how her brain determined what she was getting ready to do.

Traditionally, the left side is connected to Satan. That is also where the word “sinister” comes from.
So left-handedness comes from a satanic influence, you letting yourself be corrupted by Satan when you were in the womb.

I write right-handed, shoot rifles both left and right, play tennis & ping-pong right-handed, played baseball left-handed (batting avg .658 in little league) but was a strong switch hitter (right-handed 0.605) !

Confused ??

Polygenic predisposition.
And environmental influence.

I was left-handed.
But got switched to right.

@LuckyGuy
@Dig_Dug
@Tropical_Willie
You’re cross-dominant. :)

It’s genetics. My grandfather was left handed, but learned to use his right hand for writing so that he wouldn’t get smacked by the teacher. I’m left handed for fine hand motions (like writing and eating) but right handed for larger motions (like throwing and cutting). My brother started off left handed but my mom made him use his right hand. His handwriting is terrible. It looks like mine when I use my right hand… hmmm.

It is genetics. I have no clue where my ambidextrous came from but I can be right handed.

@raum Oooo! I love that kind of talk!

@raum Cross-dominant, sounds sexy. Maybe that’s why I can…

Nobody’s addressing the most important variable…

If you only have one arm, or limb, that would be the ultimate determining factor.

We use the tools we have.

I thought I would mention something else.
I recall reading more than one study, in which left handed people were often twins, at one stage of development before eventually the other stopped developing and the remaining fetus was born left handed.

As of the last research on the subject, to my knowledge, it wasn’t considered a scientific fact that all South Paws had once been twins. But. There was an over-representaion, noted in data collection…

The percentage of South Paws in STEM fields is higher than the percentage in liberal arts fields.

Some trivia: There have been several left-handed presidents. Maybe more than what would be statistically likely compared to the population at large, that I don’t know, but off the top of my head I remember that Gerald Ford, Ronald Reagan, George H.W. Bush, Bill Clinton, and Barack Obama were all lefties. There were others before my time, but I don’t remember who. That seems like unlikely numbers since that is 5 presidents out of 7 in the last 50 years. Is my math right? Wow.

Ha!

@JLeslie . Good observation. Ascending to such political heights, can be suggestive of some contradictory extremes.
Both great, and terrible.

60% of those lefties, were right-wing….. Go figure….

Thanks for the answers