Is laughter contagious? Is it genetically contagious

[Roland Taylor (Network Creator?)]

I was just wondering, because sometimes, when someone hears another person laughing, they begin to laugh without knowing the reason...

I had a friend who would genuinely have a fit for now apparent reason, just because of hearing someone laugh.

I have found that this is not true of everyone, but it's a behaviour that seems almost to run in families. Could it be that laughter is contagious, just as yawning is?

I have heard that yawning is passed on to others because of the human's in-built social etiquette, however there is evidence against this as well?

What do you think, is it contagious, or do we just laugh spontaneously, without reason, because of social etiquette?
Furthermore, does this behaviour run in families?

[StevenBuri]

There is no such thing as 'genetically contagious' and personality traits are not passed down from generation to generation.

[Roland Taylor (Network Creator?)]

HAHA...

They are. You need to understand some science man! :)

[StevenBuri]

No, they are not.
Personallity traits are picked up only if the son watches the adult and learns from the adult, it is not passed down genetically.
Things like the color of your eyes, wether or not you have a hitchhikers thumb are passed down because they are inheritable traits, your personality is not controlled by your DNA and therefor it cannot be passed down from generation to generation.

[Roland Taylor (Network Creator?)]

You of all should know that more is passed on than just that. Identical twins are a good example. Remember, we are so much more than skin and bones...

[StevenBuri]

You need to understand some science man.
Genetic twins arn't a good example, they think somewhat alike because their genetic makeup is identical, that doesn't mean that their personality is the same.
If you don't know this stuff it might not have been discovered when you went to school so you should go back if your so adament about it.
Personality cannot be passed down from generation to generation
A GREAT example would be Ghangis Khan who was a bloody murderer and a great fighter. The children that he had became peacemakers in the areas that he had conquered, not one stinking thing was alike, complete opposites.

This stuff has been proven scientifically, until you give me an in depth explanation about how your body works and how a womens and a mans genes are used to create a baby and how the personality traits are IN those genes then there is no argument good enough to beat mine or sciences.

And before you argue the point science hasn't proved that we evolved from apes or monkeys and it also has yet to disprove anything in the bible so you can't say 'what about that'.

[StevenBuri]

Nothing but the genes are passed from the 2 adults to the kid, that has also been proven scientifically, and your personaltiy is not dictated by your genes - if it was then that would really suck because one person might be depressed all the time while the other was laughing all the time, not fair - and I don't believe God would do that.
When someone becomes depressed its not a problem with their genes, its a problem with chemical imbalences that cause the hypothamulus and the pituitary glands to give an uneven amount of hormones to the body creating the problem.

[Roland Taylor (Network Creator?)]

HAHA! This is funny. It's not only genes...

But what about the contagious part (not running, BTW!)...

[StevenBuri]

okay, I have proven that for a fact personaltiy is not passed down from one person too another, while you just keep saying, 'actaully, yes it is'.

I think this convo is over until you can prove that personality is passed down with scientific facts other then 'it is' or twins.

[Roland Taylor (Network Creator?)]

I carry few arguments longer than 3days... But I can prove it when I have the energy... ;-)

[StevenBuri]

As for it being contagious, I reaserched that and nobody at this point in time is aware of why it seems to happen so much (concerning yawning) although it is believed that you do it in response to someone else because it gets rid of the excess Co2 in your longs and replenishes your oxygen supply but nobody knows why you do it after you see someone else do it. I would guess it was just an involuntary reaction, monkey see monkey do sort of thing.

[Roland Taylor (Network Creator?)]

I've heard many, including that it is a social instinct, or that it happens with boredom (yawning, that is)... As for laughter, I think social instinct could play a big role...

[StevenBuri]

The fact that it happens with boredom would be correct because when you get bored you almost always get sleepy or tired and you breath slower and slower causing the CO2 to build up in your body and the oxygen supply isn't enough for your heart rate, so your body tells you to yawn.