For Katherine Heigl, her family is everything. While the Firefly Lane actress may be a Hollywood star, when it comes to priorities her loved ones come first.
But her personal life hasn't always been easy and when she was just a child her beloved brother was killed in an accident which would shape her future.
SEE: Katherine Heigl and Josh Kelley's most precious family moments
Katherine was seven years old when her older sibling, Jason, was involved in a horrific car accident - he was only 15.
WATCH: Katherine Heigl's husband and children dance to Harry Styles in adorable family video
"For a long time, Jason’s death made me afraid of being too happy because things happen so unexpectedly,” she told the Sunday Times. "Your world can change and every aspect of your life is different."
In the fatal collision, Jason was thrown from the back of a pickup truck while driving out for lunch with his friends. He suffered a brain injury and died.
Katherine's family turned to the Mormon Church following Jason's death.
MORE: Katherine Heigl makes surprising confession about baby number four
READ: Katherine Heigl shares glimpse inside her incredibly wholesome homelife with children
Katherine's says her brother's death helped shape her as a mother
"Both my parents felt a great desire for answers," she told Vanity Fair. "They found an answer in the Mormon church—or answers they could live with, anyway, because there really are none.
"But I give my parents unbelievable credit for pulling it together, and I give the Mormon church a lot of credit for helping them to do that."
Katherine set up the Jason Debus Heigl Foundation in honour of her brother in 2008. The goal of the foundation is to end animal abuse.
MORE: 8 emotional celebrity adoption stories
Katherine and her husband Josh Kelley
On the website she wrote: "The foundation carries on my brother’s legacy — he had a social consciousness that not many kids have at fifteen."
Katherine has also worked tirelessly to raise awareness for organ donation.
"The accident left my brother with a brain injury, but everything else was working," she said. "So we were able to donate most of his organs."
The former Grey's Anatomy star says her brother's death helped shape her as a mother to her three children, Naleigh, 12, Adelaide Hope, eight, and Joshua, four.
MORE: Katherine Heigl's huge engagement ring has a sweet tribute
Katherine's sister was adopted and so she always knew she wanted to adopt too
"When I first became a mother, the idea of loving my children the way I did terrified me. Because it could be all taken away," Katherine - who adopted her two oldest children with her husband, Josh Kelley - said on the Today show.
"Many people have suffered through something like that," she added of her brother's death. "I have witnessed the worst thing that can happen to a parent happen to my parents. And I think that it definitely affects how you feel and what you think and what your core beliefs are about life and parenting and love."
MORE: Katherine Heigl's refreshing take on post-pregnancy weight loss
Speaking to her mum, Nancy, about how she coped with losing a child, helped pave her path as a parent.
"I've come to understand that you can survive it, and it doesn’t negate the worthwhile love. So it shouldn’t hinder that love and your passion for that love in any way — because then you’ve lost before you’ve even begun."
Read more HELLO! US stories here
Like this story? Sign up to our newsletter to get other stories like this delivered straight to your inbox.