A dad and daughter duo have gone viral this week for their heartwarming "first-day" tradition, and it's probably the most heartwarming thing you'll see today...

Now, the first day of school will always be a momentous occasion.

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A child starting school is a definitive marker of "growing up" to most tearful parents, so it's understandable that the landmark is marked and celebrated.

There are plenty of ways in which parents can mark the moment their babies fly the nest (well, kind of fly the nest)...

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But perhaps the most popular tradition is the iconic "first day of school" photograph.

Come on parents - you've all done it.

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You may have convinced yourself that you're "not that kind of parent" but, as soon as the dreaded first day of school rolled by, that camera was out and it was snapping away.

Admittedly, it's a very cute tradition.

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Who doesn't love a photo of your little one baring their teeth out of excitement for their big day?

Anyway, this tradition is usually reserved for the first day of elementary school...

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Because our children are definitely cuter at that age, right?

Well, one family has recently gone viral for their admirable dedication to this tradition.

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Ciarán Ó’Seanáin, from Belfast, Ireland, took to Twitter earlier this month to share his and his daughter's adorable first-day of school tradition.

Ciarán decided to join in with Twitter's "How It Started, How It's Going" trend...

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By sharing 3 photos of himself with his daughter, Niamh, at 3 different stages of her schooling.

Yep, instead of reserving the photo tradition to just elementary school...

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Ciarán documented his daughter's first day of high school and her college graduation day, too.

Each picture was taken from the same spot on the street outside their family home...

And, since sharing them onto Twitter, they have had close to 1 million likes and reactions.

People are loving the sentiment behind the photos...

Here are the adorable photos:

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Here, we have Ciarán and Niamh on her first day of elementary school.

The first day of high school...

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Note the awkward teenage pose.

And, finally, her college graduation day.

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And I have to say... Ciarán hasn't aged a day!

You can see his full post here.

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