My family is pretty lucky. Most of my older relatives had a full head of hair, even in their 60s and 70s.
So when one of my uncles noticed his hair was thinning out in his 40s, he became the target for a lot of teasing and jokes at family get-togethers.
Years later, after he was diagnosed with Crohn's and Colitis, we all realized that the stress on his body caused by the condition was probably to blame for his patchy hair.
There are plenty of other surprising conditions - some mild, some very serious - that can cause hair loss.
Male Baldness versus Female Baldness
Your hair naturally follows a cycle. It grows, rests, sheds, then grows again.
But when the shedding gets out of hand, it can leave bald spots or thin patches.
Men are more likely to lose their hair than women, but hair loss can affect anyone at any age.
For men, they tend to notice their hairline is receding, until it looks like the letter M or U. They may also find bald spots or patches in their hair.
Hair loss is harder to notice for women. Instead of the hairline receding, the part in the front of a woman's hair might widen. Her hair will also look thinner, stringy, and less glossy.
1. Hormone imbalances
Your body's hormones have a direct effect on hair growth and loss, and some conditions can throw them out of balance.
Hormone changes brought on by menopause will also slow hair growth.
But a thyroid disorder can also mess with your body's supply of the hormone endocrine, turning your hair thin and brittle.
This blood disorder sounds old fashioned, but it's actually still very common.
As many as one in 10 women between the ages of 20 and 50 have anemia caused by iron deficiency.
While it can strike as any age, your body needs more iron as you get older, so it's important to get a steady supply of the nutrient.
Consider taking a daily iron supplement, especially if you have other anemia symptoms like fatigue, headaches, pale skin, or cold hands and feet.
Recently polycystic ovary syndrome (PCOS) has been getting more attention in the media.
This hormone condition is actually known for causing hair growth, but on a woman's chin or chest instead of her head.
See your doctor if you're concerned you have PCOS, which can be treated with diet, exercise, and medication.
4. Your styling routine
Looking good takes sacrifice, and an intense hair care routine can seriously damage your scalp.
Chemical relaxers, hot oil treatments, and anything else involving harsh chemicals or heat can damage your roots.
Even tight hairstyles like ponytails, braids, or cornrows can stress out your scalp.
Experts recommend avoiding these harsh treatments, plus using conditioner after every shampoo and air drying to protect your scalp.
Diabetes interrupts your hair's growing period, not just on your scalp but even on your arms and legs.
Hair damaged by diabetes also tends to grow back slower than healthy hair.
Treating your diabetes symptoms will help keep your hair loss under control.
A woman's entire body goes through dramatic changes when she's pregnant, including her scalp.
You probably guessed that the hormone changes caused by pregnancy can affect your hair. But in fact many women notice their hair thinning after they give birth.
Labor is so dramatic and stressful that it can change the look of your hair for months. Thankfully, any changes to hair thickness usually go back to normal in a few months.
7. Protein deficiency
Here's one more reason to stick to a healthy diet: it will keep your hair looking fuller as you age.
If you're not a big meat eater, adding more eggs or fish to your diet instead is a smart idea.
Vegetarians and vegans can get extra protein from rice, beans, quinoa, and protein powders.
Stress will damage nearly every part of your body, but it takes a really noticeable toll on your hair.
An intense period of physical or emotional stress locks your hair in the shedding part of the growth cycle, making it look thin or patchy.
The good news is that stress-induced hair loss usually takes a month to be noticeable. By then, hopefully, your life is less stressful.
Check your medicine cabinet, are you getting plenty of vitamin A?
That's good, because it's an important nutrient for eyesight, protecting your skin, and fighting infections. But it's possible to have too much of a good thing.
High doses of vitamin A are known to cause hair loss, so if you're getting more than 5,000 International Units a day, try changing your daily supplements.
On the other hand, be sure to get plenty of vitamin B from fish, meat, starchy vegetables, or supplements. It promotes hair health.
It's sad to say, but some people are just genetically inclined to lose their hair.
Two thirds of men over 60 experience hair loss, usually caused by a combination of their genetics and aging-related hormone changes.
While hair loss caused by aging is less noticeable for women, it probably strikes them just as often.
But there is hope: products like Rogaine and Propecia can help stop hair loss or promote growth.
Alopecia areata is an immune disorder sometimes called "spot baldness."
Your body is mistaking your hair for a threat and attacking it, creating patches with thin or no hair. While alopecia is genetic, it seems that stress can bring it on too.
You can spot hair loss caused by alopecia very easily, because the condition leaves neat, round bald spots on your head.
In many cases, hair loss caused by alopecia just reverses itself over time. But it can also be treated with medication.
12. Weight loss
If you recently lost a lot of weight because of an unrelated medical condition, you may notice some changes in your hair.
Losing a healthy supply of vitamins and minerals will interrupt your hair's growth cycle, sometimes for months.
Even if your weight loss was safe and healthy, as in through diet and exercise, your hair may suffer.
13. Your medication
Odds are you have at least one medication that causes hair loss in your medicine cabinet right now.
Antidepressants, blood thinners, and skin medications like methotrexate all cause hair loss or thinning.
Even very common pain medications like ibuprofen can cause hair loss.
Remember: don't switch your medications before consulting your doctor, even if you think they're making you bald.
14. Hair pulling
Some people chew their nails, others bite pens, while some people pull their hair. Women are much more likely to be hair tuggers than men.
It's one of those annoying habits called impulse control disorders. Most people don't even give it a second thought.
But pulling on your hair every day can damage your roots, slowing your hair growth.
Ticks like hair pulling can be treated with medication, but usually it's easier to train yourself to stop.
This chronic condition causes skin inflammation all over your body, and when it affects your scalp your hairline can suffer.
In fact patients often use "Lupus hair" to describe the thin, ragged look left by the disease.
Lupus won't just thin out your hair, it can actually make it fall out in clumps all over your body.
Treatments for lupus usually reverse hair loss, but round bald patches are sometimes permanent.
Along with hair loss, look out for 10 signs your body is under too much stress.