Families can be complicated, messy things, and most of us have been shaped in some way by our relationships with the people with whom we happen to share blood — whether we like it or not.

There's no such thing as a "normal" family, but the following documentaries show how secrets and tragedy can push some bonds to the absolute limit — and, sometimes, make them even stronger.

From a twin hiding a dark secret to a father determined to find his daughter's killer, these films all show — in very different ways — the remarkable power and endurance of familial love.

'Crime Scene: The Texas Killing Fields' (2022)

Since the 1970s, at least 30 bodies, mostly women and girls, have been found on a patch of land in League City, Texas, that has earned a grim name: the Texas Killing Fields. To this day, many of the murders linked to the area remain unsolved.

As well as exploring who might be behind the killings, this film focuses on Tim Miller, whose daughter Laura went missing, aged 16, and was found dead in the fields. Miller, now in his 70s, has dedicated his life not only to hunting down his daughter's killer, but to helping the loved ones of other missing women and girls solve the mysteries of their deaths, too.

This is by all means your classic grisly, true-crime Netflix doc, but it's also the heartbreaking story of a grieving father's undying love.

'Three Identical Strangers' (2018)

This documentary tells the unbelievable tale of three identical triplets who were adopted by separate families as babies, but end up discovering one another as adults — purely by chance.

Following the brothers' lives after their reunion — including the earth-shattering revelation that their adoptions were part of a shady scientific experiment — it's a stranger-than-fiction story that simply has to be seen to believed.

'Dick Johnson Is Dead' (2020)

Filmmaker Kirsten Johnson's dad, Dick, has dementia and is nearing the end of his life. In this touching documentary, Johnson and her dad grapple with the idea of his passing by acting out the many different ways — from peaceful to comically violent — that he could end up meeting his maker.

"Dick Johnson is Dead" is a refreshing, uplifting approach to what is undeniably sad subject matter; through their shared dark humor, the father-daughter duo truly succeed in showing that death isn't all about fear — sometimes, it can be funny.

'Tell Me Who I Am' (2019)

Alex and Marcus are identical twin brothers. When Alex loses his memory in an accident at the age of 18, he relies on Marcus to tell him everything about their lives. As Marcus fills in the gaps for his brother, he invents happy childhood memories — and omits the dark ones, to spare Alex the pain they had previously both been living with. Eventually, though, the secret comes out.

In this incredibly moving film, we see Marcus attempt to justify his lies to Alex and grapple with his own suffering, while Alex struggles to come to terms with a deeply traumatic childhood that he can't even remember.

A story of brotherly love, trauma and the things we do to protect those we care about, "Tell Me Who I Am" is a tough watch — but it's like no other documentary out there.

[Image credit: YouTube]