A mum and her three children died when she steered her car on to the wrong side of the road and crashed head-on with a lorry, an inquest has heard.
The crash on the A40 in Oxfordshire caused the deaths of Zoe Powell, 29, and her children Phoebe, eight, Simeon, six, and four-year-old Amelia.
Mrs Powell's husband Josh and their daughter Penny, who was 18 months old, survived the crash on 12 October 2020.
A coroner said fatigue and distraction may have caused her to swerve the car.
Mrs Powell was driving the family home from her in-laws' house when the collision with the 36-tonne lorry happened near a railway bridge at 21:50 BST, Oxfordshire Coroner's Court heard.
Her Subaru people carrier was fitted with an onboard computer, which showed it had been in cruise control and was steered sharply to the right moments before the collision.
Witnesses reported the car had been driving normally and within the 60mph speed limit immediately before the crash.
Lorry driver Adao Patricio, who suffered only minor injuries, said he had no time to react to the car crossing into his path.
The court was told Mr Powell, who had been in the passenger seat, had no recollection of the crash and so it could not be known for certain what caused his wife to swerve.
Darren Salter, Oxfordshire's head coroner, said he had considered whether Mrs Powell had been fatigued or asleep, distracted by the children in the backseat, or if it was a deliberate act.
He said although the possibility of it being deliberate could not be ruled out, there was no evidence she had ever considered harming herself or her children.
"I think it is more likely that there was fatigue or distraction, or a combination of the two," the coroner said.
He added that Mrs Powell, a writer and artist, had been described as "devoted to her children, marriage and faith".
A conclusion of death by road traffic collision was recorded.
In a statement released following the hearing the family said: "Whilst there is much that we will never fully understand about the crash, it is helpful to comprehend some of the potential explanations of what led to it.
"The possibility that such a small distraction may have caused such a horrific accident should act as a painful reminder for everyone that roads are dangerous places; the actions of a single moment have wrecked an entire family and had a lasting impact on everyone around them."
The family added that Mrs Powell, Phoebe, Simeon and Amelia had left them with "an abundance of happy memories" and they were now taking comfort from their faith in Christianity.
The deaths occurred just months after the family lost everything in a fire at their home.