Is sense of humour learned or innate?

People raised alike differ in humour, so the difference must be in them

Question: Is sense of humour learned or innate?
Position‹2 of 2: A sense of humor is innate
Argument‹2 of 2: People raised alike differ in humour, so the difference must be in them

The argument

Proponents of this position point to the limits of upbringing as an explanation. Siblings raised in the same household, exposed to the same jokes, the same comedy and the same family habits, routinely differ in how funny they are and in what amuses them. One is quick and irreverent, another earnest and slow to the joke. If humour were simply absorbed from the surrounding environment, those raised in the same environment should emerge with much the same sense of it, and they do not. The argument extends to how early and how stubbornly these differences show. Temperament in children is apparent well before formal socialisation: some are drawn to silliness and mischief from the start, others are not, and the tendency tends to persist. Nor does it respond readily to instruction. A person can be taught the mechanics of a joke, the structure of a pun and the value of a pause, and still not be funny; another can break every rule and be funny anyway. A capacity that resists teaching and survives changes of setting looks like a disposition rather than a lesson. Proponents therefore distinguish polish from possession. Practice and exposure can sharpen a sense of humour, supply it with material and teach a person when to deploy it — none of which is denied. What practice cannot do, they argue, is install the underlying quickness in someone who lacks it, which is why comic talent is recognised as a talent. Because people given the same comic environment still differ markedly and persistently in humour, this argument concludes, the difference lies in what they were born with.

Premises

[P1]Siblings raised in the same household with the same comic influences still differ markedly in their sense of humour. [P2] These differences appear very early, persist through life, and do not yield to instruction in how humour works. [P3] A capacity that varies between people given the same environment and resists teaching is a disposition rather than something acquired. [C] Therefore a sense of humour is innate, with practice refining rather than supplying it.

Counter-arguments

Those who hold humour to be learned reply that siblings do not in fact have identical social experience: they differ in birth order, friendships, schooling, attention received and the responses their early attempts met, and those differences compound. They add that the claim is refuted by the many people who were awkward in youth and became funny later, and who can name what they changed. A trait fixed at birth could not be deliberately acquired in adulthood, yet it routinely is.

Rejecting the premises

[Rejecting P1] A shared household is not the same comic environment. Siblings differ in the age at which they met a given influence, in friendships, in reading, and in which of the household's jokes were addressed to them. The premise needs identical input and has only a shared address. [Rejecting P2] That the differences do not yield to instruction treats formal teaching as the test of learning, when humour is acquired by imitation and feedback rather than by lessons, so resistance to instruction shows little. [Rejecting P3] Variation between people in similar environments combined with resistance to teaching also describes accent, handwriting and taste in music, none of which is innate, so the inference the premise draws is not generally available.