Penis size has been researched somewhat extensively—myths on how to decipher what’s going on in someone’s pants, without sneaking a literal peek, have been whispered through society uncontrollably for centuries. Now, don’t lie to me, we’ve all at some point grazed our eyes over a man’s hand or a shoe size. Then again, a penis’ size preference (in a sexual partner’s case) is just that: a matter of preference, and I cannot speak for all of you out there as to what you’d like to be surprised with. But nonetheless, we’re here to discuss what makes a penis reach a certain size. Is it genes? And while we’re at it, you can rest assured that I’ll find out whether hands and feet play a part in the assumptions of what one’s got going on down under.

According to research, and the evidence that comes with it, genes do actually seem to play an important role in the growth of a guy’s peen, which is a fact not to astonish you—however, what might, is that the genetic material mostly comes from mothers. Essentially, for the first seven weeks of fetal development, both male and female fetuses look the same, but if you were given a Y chromosome from your father, week eight will be the turning point in developing male genitalia, penis included.

If you get another X chromosome from your father (either an X or Y will be added onto an existing X chromosome from your mother) you’ll get a set of ovaries, penis not included. This means, in non-scientific terms, dad decides whether you’ll be sporting a penis or vagina by the time you’re out the womb, but mum does the shaping of what comes out of it.

That being said, director of sexual health and medicine at Weill Cornell Medicine in New York, Darius Paduch, told Mel Magazine that “If a father has a bigger penis, the son’s will probably be similar in length.” Although not guaranteed, he continued “Men have one X chromosome, and women have two. Since boys always inherit the X chromosome from the mother and the selection of that X chromosome is random, this can explain why one brother may have inherited genes for a large penis from one of the mother’s X chromosomes, but another brother inherited an average-size penis from the other.”

Dick growth is ultimately out of the dick’s control, and most fall within an ‘average’ range (don’t @ me for saying the word average, I’m talking numbers here). The average erect penis size is 13.12 centimetres, that’s 5.16 inches long, according to a study by the British Journal of Urology International. The ‘above average’ is 16 centimetres, or 6.3 inches long. Yes, right about now was the exact point that I went to look for a ruler. Anyway, moving on, so what about girth?

Paduch stated that “The penis grows in thickness and length with the onset of puberty and stops growing in length in mid-to-late puberty.” He added that “Its growth is regulated or driven by two hormones: testosterone and growth hormone. Testosterone seems to relate more to length, and growth hormone to girth, but we need both of them. What’s fascinating is that despite the fact that men produce testosterone all their lives, the penis doesn’t grow indefinitely, though the girth may increase slightly with age even after puberty.” This does not mean you should go supplementing, hormonal exposure can speed up growth, but mainly in fetal development.

When it comes to assuming what size your date’s packing in his pants though, unfortunately, there isn’t much concluded evidence as to whether big hands or feet correlate to the size of one’s member, at all. When all studies are compiled together, the most consistent correlation is actually height and overall proportion, but again, it’s an iffy argument. Like anything though, you can always find the answer you’re looking for when you go down the Google rabbit hole yourselves, but I’m just here to tell you how it is.

At the end of the day it’s, as always, better not to assume at all. Besides, size doesn’t really matter, regardless of a sexual partner’s personal preference. Voicing your wants and needs, your ‘keep doing that’ and ‘let’s switch it up’ comments matter far, far more when it comes to sexual pleasure. You can’t control your partner’s preferences, or penis size, or love for that matter, but you all can (and should) have hot, moreish, lip-biting sex. If you are needing a little help to fuel the flames or break the ice, try a sex game.