Yes, penis size is genetic, but it’s a little more complex than your parent having a smaller/bigger/hairier peen so yours will turn out like that, too.

Here’s what you need to know.

You can thank whoever has a Y chromosome for the fact that you have a penis at all.

People assigned male at birth (AMAB) inherit the Y chromosome from a parent who was born with a penis, just like people assigned female at birth (AFAB) inherit the X chromosome from a parent who was born with a vulva.

As far as sex organs go, all fetuses look the same up until the seventh week of development.

After that, testes and all the rest start developing thanks to that Y chromosome.

But the Y chromosome doesn’t necessarily determine the type of penis you’re packing.

Your other parent’s contribution, your own unique genes, and other factors (more on those in a minute) play into your penis size, shape, and other features.

And yes, there are several types of penises.

Nope. This is where the X chromosome comes into play and shakes things up.

AMAB folks have one X chromosome and AFAB individuals have two.

AMAB folks inherit the X chromosome from an AFAB parent, and the selection of that chromosome is random.

You might have inherited genes for a larger penis from one of those X chromosomes, and your sibling could have inherited an average-sized penis from the other. It’s basically a crapshoot.

And before you ask: Yes, even twins can have different-looking Ds.

All that said, family members do tend to have similar features. While it isn’t guaranteed, there’s a good chance that you and your siblings share some similarities down there.

Yes, and they’re probably not the ones you think.

Contrary to the stereotype, race has no bearing on dick size.

Masturbation isn’t a factor in penis size either. It’s just a myth that frequent solo sex will make your D smaller or bigger.

Now that we’ve got that out of the way, let’s take a look at some factors that can actually influence size.

Your genes

We all have traits — or phenotypes — that are individual to us.

For example, you could have a turned-up button nose even though your parents’ noses lean more to the toucan side of the spectrum.

These traits could be the result of what’s called de novo genes. Everyone has these gene mutations, though how many varies from person to person.

These are genes that have changed slightly from your parents’ line and are all your own.

Exactly how these genes are born is still a bit of a mystery, but we do know that they can influence your physical traits — including your penis size and overall appearance.

For instance, you and your parent may share a similar length and girth, but yours could lean left while theirs hangs right.


Hormones play a role in your penis size from the start.

Androgens determine penis size during early fetal development. Throughout puberty, testosterone and growth hormone regulate penis growth, including length and girth.

It isn’t just the hormones your body makes that affect penis size, though. The hormones you’re exposed to in your environment while your body is developing also impact penis size.

But instead of making your D bigger, these hormones have the opposite effect — not that penis size matters in bed, but still.

Exposure to environmental estrogens — aka a female sex hormone — during puberty has been linked to shorter-than-average penises.

Chemicals called endocrine disruptors can also have a negative effect on your penis. And the rest of your body, for that matter. These chemicals are found in things like pesticides, plastic containers, and some detergents.

Poor nutrition

Malnutrition in the womb and during the first few years of life can impact hormones and affect your growth and development.

We aren’t just talking your height and weight — organ development, including your reproductive organs, can also be affected.

It’s hard to say. Dicks are like snowflakes so no two are ever exactly alike.

They do the most growing during puberty, but puberty and penis growth happen at different times and speeds for everyone.

One study found the average growth rate to be less than half an inch per year from ages 11 to 15, but this isn’t set in stone for every peen.

You don’t have any control over it anyway, so try not to stress.

Typically, your dong’s as long as it’s going to get by the age of 18 or 19, and it reaches maximum girthy-ness shortly thereafter.

For some, the penis can stop growing a year or two later than that, depending on when puberty starts.

For reference, puberty usually begins between the ages of 9 and 14 and lasts up to 5 years or so.

According to a 2014 study, the average penis is 3.6 inches long while flaccid and 5.2 inches erect.

Try not to get too hung up on the number. For starters, the study only looked at a small portion of the world’s penis-wielding population.

Also, most people believe they’re smaller than average when they’re not. In reality, around 95 percent of people with penises do fall within the average range.

Finally and most importantly, size doesn’t make a diff where it matters most, which is in the bedroom… or backseat of a car… or the airplane lavatory…

Your love muscle (which is actually an organ) is the size that it is and there’s nothing you can do to make it bigger or smaller, aside from surgery.

Penis stretching exercises may increase size temporarily, but any evidence of this is anecdotal and doing it wrong could cause damage.

It’s possible to create the illusion of a bigger or smaller dick. Shaving your pubes so your D is on full display can make it appear bigger. On the flip side, a full bush can appear to shrink your D if you’re worried that it’s too long.

Your best bet is to learn to make the most of what your parents — or de novo genes — gave you.

The right sex positions can help you make the most of your size so you and your partner get off right.

Wanna master these moves? Check out How to Have Great Sex with a Bigger-Than-Average Penis and How to Have Great Sex with a Smaller-Than-Average Penis. You’re welcome.

What’s in your jeans isn’t only about the genes your parents gave you, but it’s certainly a major factor. When it comes down to it, though, as long as your penis is healthy, size isn’t really all that important.

Adrienne Santos-Longhurst is a freelance writer and author who has written extensively on all things health and lifestyle for more than a decade. When she’s not holed up in her writing shed researching an article or off interviewing health professionals, she can be found frolicking around her beach town with husband and dogs in tow, or splashing about the lake trying to master the stand-up paddleboard.