By regulative I mean that in order to see a major effect, you already need to have a major state. A person with no aggression is not going to get aggressive based on testosterone. A person that is already aggressive will have that aggression regulated if one artificially increasing the circulating testosterone, most often by exaggerating the aggression in a context aware way. For example, a person who has a tendency for road rage won't be more likely to shoot someone, but they might honk the horn more or yell more loudly. Regulative effects don't cause things to happen, but rather modulate what already exist.
Puberty and pregnancy has an other thing in common, in that it both cause changes in the persons neurons. Its speculated the reason that a womans body during pregnancy do this is in order to make it easier form memories and bond with the newborn baby. Its been suggested that some typical pregnancy behaviors is thus a result of those changes to the neurons. I would strongly suspect that hormone levels have a regulative role in facilitating the rate of the changes, but I doubt if measuring the hormone level would be a predictor for how much of a change actually happened.
To bring out an analogy, taxes has an regulative effect on wealth, but its a not a predictor for it. If I selected random individuals over the world and only looked at where they live and how much percent that they pay in taxes, it will tell me nothing about who is rich and who is poor. I have a better time looking at living expensive and food prices, but even that is a poor method to predict how much wealth someone has. I would thus not describe taxes as having a significant effect on wealth, and that wealth per adult is the result of a complex system.
I think you may mean (and if this is the case I generally agree) that when hormones trigger behaviors such as road rage, those behaviors have already been learned. Likewise, testosterone is unlikely to cause someone to shoot another driver because significant inhibitions against that behavior have been learned.
But hormones have an effect even in early childhood and before birth, when no behaviors have been learned yet. Prenatal hormones affect brain structure, and studies have found a link between hormones in children as young as 3 months and their choice of toys.[1]
[1] http://www.livescience.com/22677-girls-dolls-boys-toy-trucks...
And those quotes are not quite "hormones (within natural occurring levels) have very minimal effect on emotion".
"the impact of estrogen on emotion varies"
And another quote from the study you quoted (Effects of testosterone on mood, aggression, and sexual behavior in young men: a double-blind, placebo-controlled, cross-over study):
"Increased circulating T was associated with significant increases in anger-hostility from baseline (mean score = 7.48) to wk 2 (mean score = 10.71)"
7.48 to 10.71 doesn't seem like a very minimal change.
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Since you quoted WebMD (perhaps a useful summary) I will as well:
"It's clear that estrogen is closely linked with women's emotional well-being. Depression and anxiety affect women in their estrogen-producing years more often than men or postmenopausal women. Estrogen is also linked to mood disruptions that occur only in women -- premenstrual syndrome, premenstrual dysphoric disorder, and postpartum depression."
And from another article:
"Declining estrogen levels associated with menopause can cause more than those pesky hot flashes. They can also make a woman feel like she is in a constant state of PMS (premenstrual syndrome). Unfortunately, these emotional changes are a normal part of menopause."
"Some of the emotional changes experienced by women undergoing perimenopause or menopause can include: Irritability, Feelings of sadness, Lack of motivation, Anxiety, Aggressiveness, Difficulty concentrating, Fatigue, Mood changes, and Tension."
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Perhaps we can agree.
I'm not sure exactly what you mean by regulative, but I agree that emotions are complicated and hormones are not the only influence, nor is the relationship a simple cause and effect.
On the other hand, there's significant evidence that hormones do effect emotion, including perhaps the most striking example which I somehow forgot earlier: puberty. And their prenatal effect on the structure of the brain.
Would you agree hormones do effect emotions, but aren't the only factor, and the relationship is complicated, unpredictable, and varies between individuals?