Weatherston (33), a former University of Otago economics lecturer, spent more than two hours in the witness box yesterday afternoon detailing his life before his arrest for killing his ex-girlfriend, Sophie Elliott on January 9 last year.
The accused said he was born and raised in Dunedin, the youngest of three children, was always top of his class at Green Island Primary School, near the top of the class each year at Kaikorai Valley High School and left as dux.
He described his embarrassment when he was 11 and had to get glasses after failing to achieve 100% in a mathematics test.
He had been unable to see the blackboard and the teacher publicly commented on his failure to gain a perfect score.
Weatherston said he was terrified of being teased about his glasses and upset when the optometrist said he would not be able to see what was on his plate by the time he was 19.
It was several months before he would wear his glasses.
But the feared teasing and derision did not happen.
He had been extremely reluctant to leave his mother who had to walk him part of the way to school when he was younger.
He would go through phases of feeling unwell and wanting to come home from school.
He did not want to leave primary school where he was "a big fish in a small pond".
His sister went with him on his first day at Kaikorai Valley High School.
He did not cope well with away trips for sport.
His parents usually came with him and they would stay at motels, while his friends were being billeted.
He won several titles and medals in athletics.
When he finished high school, he felt pressured to go to university but, after two weeks decided to work at an accountancy firm, while continuing undergraduate studies.
He saw his job as a means of providing funding for university, so he would not have to get a student loan.
Weatherston said he began full-time academic studies for a bachelor of commerce degree in 1994, achieving A-plus passes in all but one paper.
But a tendency to over-analyse resulted in illness-causing stress and he had to sometimes sit special exams.
In 2002, he went to the Treasury for nine months but became ill, missing his family and feeling dissatisfied with a job where he was not sure he was being taken seriously.
He had also received offers of funding for Harvard and Princeton universities.
He wanted to come back to Dunedin to be safe, to be close to his mother and to be in a non-challenging situation.
He began seeing a psychotherapist in 2003 and met his girlfriend in 2004, enjoying the relationship, but also feeling insecure and having some concerns.
Weatherston will continue his evidence today.
