This is a spooky, unsettling Finnish horror movie that also comments on the facades lurking beneath appearances, particularly appearances in suburbia. Hatching can be enjoyed simply as a monster story, but there are obvious themes at work here, and director Hanna Bergholm offers pointed commentary on the plastic smiles of surface-level perfection (exemplified by the wicked smile of the image-conscious mother, perfectly portrayed by Sophia Heikkilä), the stark contrast between public image and the reality behind the closed doors, parents who push way too hard and expect their kids to overachieve, and perhaps a really odd tween coming-of-age story. Or, again, if you don't want to read that much into it, this could just be a tale of a monster that goes after the perceived enemies of its "mother."
There are exaggerated archetypes, exaggerated symbolism (giant egg that breaks through the teddy bear that it was placed inside to keep warm while still a normal sized egg, for instance), and exaggerated fashion choices (the dad's taste in clothing isn't really needed to convey that he's a passive cuckold in this story), and it all somehow works. It's the menace lurking throughout the story that helps to keep it entertaining, and when the payoffs to the suspense happen, the images are truly unnerving. They make all of this look easy, but as so many horror movies prove, it's not easy to make a horror movie this weird and fun to watch.