Does Every Baby Start Out as a Girl? The Surprising Truth

The Basics of Gender Development: How Does it All Begin?

Well, this is a question that comes up often. And I can totally understand why people wonder about it—there’s a lot of confusion around how gender develops before birth. So, let’s break it down a bit.

Actually, when an embryo is first developing in the womb, it doesn't have a clear gender. In the early stages, all embryos start out with the same set of undifferentiated structures. That means, biologically speaking, they look like potential females, but they haven’t developed distinct male or female features yet. Confused? Let me explain more.

Chromosomes: The Blueprint of Gender

Every person has a unique set of chromosomes, and these chromosomes play a huge role in determining gender. Most people have 46 chromosomes, arranged in 23 pairs. The 23rd pair, however, is special—it's the sex chromosomes.

• XX chromosomes typically result in female development.
• XY chromosomes typically result in male development.

At conception, the sperm (which carries either an X or a Y chromosome) fertilizes the egg (which only carries an X chromosome). So, if the sperm carries an X chromosome, the resulting baby will develop as female. If it carries a Y chromosome, the baby will develop as male. But here’s the interesting part: the initial stages are the same.

What Happens During Early Development?

Okay, so now we know that, genetically speaking, a fertilized egg doesn't "decide" on its gender right away. But here’s where it gets more intriguing.

The Default Gender is Female

Actually, in the very early stages, the default is female. That’s right—biologically speaking, the body starts its development with female structures. For the first few weeks of pregnancy, all embryos have the same kind of tissue in the genital area, which can develop into either male or female organs depending on what hormones are released later on. It's kind of like a "blank slate" moment.

Honestly, I didn’t realize this until I started reading up on it myself. For a long time, I just assumed everyone started out as either male or female from the very beginning. But nope, it’s more like the body has a "default setting" for female development that needs to be "turned off" if the embryo is going to develop male characteristics.

The Role of Testosterone: Turning the Tide

Here’s where things get a bit more complicated. Around 7-8 weeks into pregnancy, if the embryo has an XY chromosome combination (indicating a male), it will start producing a hormone called testosterone. This hormone signals the body to start developing male reproductive organs, and the default female structures begin to regress. Without testosterone, the embryo would continue developing along the female path.

I remember having a conversation with a friend recently who had no idea about this, and they were surprised to learn that it wasn’t "automatic" that every embryo starts out as a boy or a girl. The role of hormones like testosterone totally determines this shift. It's mind-blowing, really!

How Does This Affect Intersex Individuals?

So, this process of gender development sounds pretty straightforward for most babies, but what about those who are born with intersex traits?

Intersex Conditions: More Common Than You Think

Intersex refers to a variety of conditions in which someone’s reproductive or sexual anatomy doesn’t fit typical definitions of male or female. In some cases, someone’s chromosomes might be XX, but their body may respond to testosterone in such a way that they develop male-like characteristics, or vice versa. There are many variations of this, and it can occur naturally during fetal development.

I think this is something that people don’t talk about enough, but intersex conditions really highlight how complex human biology can be. Sometimes, the body doesn’t follow a “standard” path, and it’s not always easy to categorize a person’s sex based on their appearance or chromosomes alone.

Conclusion: Does Every Baby Start Out as a Girl?

Honestly, when I first started researching this, I thought the answer was pretty simple. But now, I see it’s actually a pretty nuanced question. So, in short—yes, all embryos do start with female development structures. However, it’s not until around the 7th or 8th week of pregnancy that male embryos, with the help of testosterone, start to develop male characteristics. Before that, everyone is on a similar path. But remember, it’s the interplay of genetics and hormones that determines how each individual develops.

Next time someone asks you, “Does every baby start out as a girl?”, you can confidently say, “Well, not exactly, but it’s kind of true in the early stages.” It’s one of those fascinating things about human development that I’m still trying to wrap my head around!

Is 165 cm normal for a 15 year old?

The predicted height for a female, based on your parents heights, is 155 to 165cm. Most 15 year old girls are nearly done growing. I was too. It's a very normal height for a girl.

Is 160 cm too tall for a 12 year old?

How Tall Should a 12 Year Old Be? We can only speak to national average heights here in North America, whereby, a 12 year old girl would be between 137 cm to 162 cm tall (4-1/2 to 5-1/3 feet). A 12 year old boy should be between 137 cm to 160 cm tall (4-1/2 to 5-1/4 feet).

How tall is a average 15 year old?

Average Height to Weight for Teenage Boys - 13 to 20 Years

How to get taller at 18?

Staying physically active is even more essential from childhood to grow and improve overall health. But taking it up even in adulthood can help you add a few inches to your height. Strength-building exercises, yoga, jumping rope, and biking all can help to increase your flexibility and grow a few inches taller.

Is 5.7 a good height for a 15 year old boy?

Generally speaking, the average height for 15 year olds girls is 62.9 inches (or 159.7 cm). On the other hand, teen boys at the age of 15 have a much higher average height, which is 67.0 inches (or 170.1 cm).

Can you grow between 16 and 18?

Most girls stop growing taller by age 14 or 15. However, after their early teenage growth spurt, boys continue gaining height at a gradual pace until around 18. Note that some kids will stop growing earlier and others may keep growing a year or two more.

Can you grow 1 cm after 17?

Even with a healthy diet, most people's height won't increase after age 18 to 20. The graph below shows the rate of growth from birth to age 20. As you can see, the growth lines fall to zero between ages 18 and 20 ( 7 , 8 ). The reason why your height stops increasing is your bones, specifically your growth plates.