The Ranelagh teenager is well known to followers of fashion as she has appeared in fashion shoots for some time now and has been long tipped for the top.
Premier Model Management -- who have also managed Cindy Crawford, Linda Evangelista and Christy Turlington -- have a flat in London ready for Thalia to use after she completes her Leaving Cert this summer and predict she will take London by storm.
Thalia, who is currently studying at Teresian School in Donnybrook, has already featured in London Fashion Week.
The schoolgirl is following in the footsteps of her mum Susan, who also modelled and is on hand to offer her student daughter some valued words of wisdom.
In an interview with this week's VIP, Thalia credits her mum and family with keeping her feet firmly on the ground.
"We have a great relationship. I can be very honest with her amid can talk about boys. She's great," she said.
And mum-of-three Susan turned to the lens once again as she posed proudly alongside her youngest daughter.
Susan Heffernan modelled with Morgan The Agency -- the same agency that looks after her daughter in Ireland. As a result, both she and Thalia's dad Gerald have been very supportive.
"They don't go on about it, but I know they are very proud of me. They want to keep me grounded, especially during the Leaving Cert year."
Not surprisingly, Thalia looks to her model mum for styling tips as well as to her elder sisters, Anna (26) and Georgia (24).
"My mum is quite stylish, and my eldest sister, Anna, has been really cool -- I've always looked up to her," Thalia said.
While most of us would love to look like Thalia, the 17-year-old thinks she looks a little awkward and lacks confidence when she's away from the camera.
"I don't have typical Irish features, so I don't look like your average girl on the street. I'm tall, a bit lanky and a bit awkward," she told VIP.
"In my head, I'm not a model -- I'm the ugliest girl in the year! I don't have the same confidence that I do when I'm modelling," she added.
While the youngster, tipped by many as the next supermodel, says that nasty comments from her other girls can get her down.
"I don't think it's as much jealously as it is bitchiness. I have experienced a lot of it over the last few years. It can make me sad and it's hard to take sometimes. I've a map set out for me, and I think a lot of people my age don't. They can make their lives a lot better than mine; all they need to do is work at it."