As men age, they're most likely to notice it on their heads first.

Hair loss affects 20 per cent of men in their 20s, 30 per cent of men in their 30s and so on, according to hair expert Dr. Alan Bauman of Bauman Medical Group in Florida.

"There are millions of people across North America who experience hair loss," he says.

For the most part, hair loss is genetic, but the speed and pattern of baldness doesn't necessarily have to be based on your parents, Bauman told The Huffington Post Canada. "Other factors like the shape of your hairline and the colour of your hair both affect balding patterns."

And if you're smoking a pack a day, chances are this process is accelerated. Bauman says being overly stressed at work or at home, falling into bad smoking habits and lacking nutrients for strong hair and health are all ways men and women start noticing hair loss earlier. People who also tend to overuse heated tools or chemical-based sprays have higher risks of damaging their locks.

In March, researchers from the University of Pennsylvania released findings about a potential cure for baldness after discovering high levels of a protein called prostaglandin D synthase (PDG2) in bald areas of the scalp. The study claimed that creating pills with PDG2 blocking properties could help "cure" baldness, and hope to have an option on the market within the next five years.

But for the time being, one out of four Canadians don't know who to ask for help when dealing with the loss of their hair. This number doesn't surprise Bauman, who adds that some men avoid check-ups and can lose more than 50 per cent of their hair before they realize it's happening.

It's not just the fellas, either. For women, taking particular drugs, being highly stressed and using hot tools on your head can all lead to baldness.

SEE: Can you spot the matching hairline? To show the affects of genetics and balding patterns, Dr. Bauman listed seven celebrity sons that he believes will look more and more like their dads as they age:

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  • Tom And Colin Hanks

    For the Hank family, Bauman says the receding hairline is an easy way to notice how family genetics can affect hair loss. <br> <em>Actors Tom Hanks and Colin Hanks on March 10, 2009 in New York City.</em>

  • Jerry And Ben Stiller

    Ben Stiller and Jerry Stiller are specifically interesting because of their hair colours. Bauman predicts Ben could look like this in the future. <br> <em> Ben Stiller and Jerry Stiller at the Urban Zen Center At Stephan Weiss Studio.</em>

  • Scott And James Caan

    Another interesting pair are the Caans. Bauman says James may have undergone a hair transplant, which means Scott should be looking into hair loss earlier. <br> <em>Actors James Caan (L) and Scott Caan on May 3, 2010 in Hollywood, California. </em>

  • Donald and Keifer Sutherland

    These two Canadians already look alike. Keifer Sutherland could be going grey -- but hey, at least he has a full head of hair. <br> <em>Actors Donald Sutherland and Kiefer Sutherland on September 11, 2011 in Toronto, Canada.</em>

  • George And Nick Clooney

    It looks like George Clooney may just be going into a light shade of white as the years go by. Good for him. <br> <em>Actor and activist George Clooney (L), accomapnied by his father Nick Clooney, on March 16, 2012 in Washington.</em>

  • Princes Charles And William

    Though Prince Will gets all <a href="http://www.huffingtonpost.com/2011/01/22/did-prince-williams-baldi_n_812595.html" target="_hplink">sorts of attention for his hair</a>, based on his dad, we don't think people need to worry about the Prince going bald. <br> <em> William, Prince of Wales watch Gary Barlow in concert in aid of The Prince's Trust.</em>

  • Donald Trump And Donald Jr.

    Donald is known to have an "infrastructure" of hair, Bauman says. After his dad had to <a href="http://www.vanityfair.com/politics/features/2011/04/donald-trump-real-hair-proclamation-201104" target="_hplink">prove his hair was real</a>, Donald Jr. may not have to worry about wearing a hairpiece.<br> <em>Chairman and CEO of the Trump Organization & television personality Donald Trump and Executive Vice President at The Trump Organization, Donald Trump Jr.</em>

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