In the past six years as a house husband, Mr Chua has learned to be careful with his grocery spending as he would have to fork out the extra money whenever he exceeded the budget, he added jokingly.
"I did not have any training before, but I learned to bathe them, feed them and take care of them when they are sick.
"I call it a parent's instinct. Be it the dad or the mum, it is the parents' instinct to look after their children. I had learned to identify their cries, whether it was a cry that they had wet their diapers or a cry for milk," Mr Chua said.
As the twins grew older, Mr Chua attended toddler classes with them. It was inevitable that he received curious stares from other toddlers' mothers. But Mr Chua took the stares in his stride. He said: "I was the only man in my kids' class. And unlike them, I didn't just look after one kid, but two. I took the initiative to interact with them and even gave them some parenting tips that I had learnt."
Mr Chua said his family and friends supported his decision to care for the children, much to his surprise.
He said: "They told me that I have made the right decision and they actually envy me for being able to do it.
"There are always sacrifices in life. Sometimes money can create a lot of family problems, but I am glad that it has never been our problem.
"When Rachel and I decided on this arrangement, we knew what we were getting into. We had our little struggles and we don't envy others who are able to take their children on holiday during every school holiday. We need to strike a good balance."
On her part, his wife has never doubted his ability to take care of the children.
She said: "In my previous job, I would get very stressed out with the office politics and I would ask Peter if we could switch back our roles. But I also knew that I wouldn't last more than two months at home."
Madam Foo admits that her husband has done a better job than she ever could.
When Madam Foo returns home in the evenings, Mr Chua would patiently wait for her to settle down and have her dinner before lending her a listening ear.
He said: "I would listen to her talk about her work in the office and sometimes give her my advice. That's what a husband is for."
It is something his wife greatly appreciates.
Madam Foo said: "Sometimes I can get very carried away with my work and Peter is always there to remind me that our family is equally important."