As the Lindsay Clancy murder trial approaches closing arguments, jurors will soon be asked to decide whether the former labor-and-delivery nurse is criminally responsible for killing her three small children in January 2023.At the heart of the legal question for jurors is whether Clancy knew what she did was wrong and was capable of following the law. Clancy's defense lawyer, Kevin Reddington, has argued instead that she suffered from postpartum psychosis that winter evening, which left her unable to leave her children safe before she tried to kill herself in a suicide attempt that left her paralyzed.The trial has captured the nation not only because of the thorny questions about criminal responsibility and mental health treatment it has highlighted, but also because of the painful human story at the heart of the case: that three little children, Cora Clancy, Dawson Clancy and Callan Clancy, were killed by one of the people most responsible for their care.During the trial, witnesses have testified about what those three small children were like, and what kinds of childhoods they had leading up to their deaths. The picture painted is one of happy children who were full of energy and enjoyed family trips to places like Cape Cod and Boston's Museum of Science.Here's a look at what witnesses have shared about each of the Clancy children:'Liked taking care of people': Cora ClancyCora Marie Clancy was born on Dec. 24, 2017, and turned 5 years old about a month before she died. The Clancy family had a birthday party for her at Nova Trampoline Park in Plymouth, Massachusetts, after the holiday period, on Jan. 7, 2023, Patrick Clancy testified. A short video clip played in court showed Cora wearing a pink crown while kids sang the "Happy Birthday" song for her.Elaine Rossi, a nanny for the Clancy family, testified that Cora was "a girly girl." She enjoyed arts and crafts and playing with her "Fresh Mart" child supermarket play set, Rossi said."She was lovely," Rossi added.Patrick Clancy testified that his daughter was into princesses and had a lot of friends."She just liked taking care of people," he said.On Cora's 4th birthday, her mother posted on social media that her daughter was growing into "the most perfect version of herself" and was “the sweetest gift God ever gave me."'Rambunctious, funny, silly': Dawson ClancyDawson William Clancy was born on Sept. 30, 2019, and died about four months after his third birthday.The young boy was into firefighters and trucks, and liked watching the "Paw Patrol" TV series, according to Patrick Clancy's testimony. "Paw Patrol" focuses on a boy who leads a team of search-and-rescue dogs.“Dawson was full of energy, rambunctious, funny, silly," Rossi, the family's nanny, testified.On his final day of life, Dawson played outside in the snow, building a snowman with his sister. Patrick Clancy remembered seeing Dawson sitting on the couch eating chicken nuggets and green beans when he left to run errands in the evening of Jan. 24, 2023, at which point Lindsay Clancy has said she strangled Dawson and his siblings before trying to kill herself.'Just a happy baby': Callan ClancyCallan Patrick Clancy was born on May 26, 2022. He was just 8 months old when he died."He was the happiest, sweetest, easiest baby. He was just a love," Rossi, the nanny, said in her trial testimony.Patrick Clancy also described his youngest child as "just a happy baby."Callan survived for three days after his mother, whose lawyer has argued she was suffering from postpartum psychosis, tried to kill him by strangulation. He died in a hospital on Jan. 27, 2023.