Splashing water may become a new mahjong strategy as it distract competitors -- some Chongqing residents play mahjong at a water park to have fun while cooling off, July 8, 2014.[Photo/Chinanews]

People are naturally asking why the nanny would start the blaze in the high-end residence in Hangzhou, especially since she was reportedly treated well by the family. Apart from a decent salary, the couple reportedly loaned her 100,000 yuan ($14,870) when she told them she needed the money to purchase a property in her hometown.

Some assume the couple's total trust in the nanny cost four lives, while some urged households to think twice before hiring a nanny. But the tragedy in Hangzhou, if it proves to be the act of the nanny, was because of her psychological issues not her job.

Judging by the nanny's heavy debt and record of frequenting casinos, it can be concluded that she has long been troubled by her compulsion to gamble and her inability to cover her losses, hence her desperate acts like theft and possible arson that make little sense to the clear-minded.

So if the nanny does prove to be guilty, it is her obsession with gambling that should be held responsible for her acts. Gambling can easily become addictive to some, constituting a mental disorder .

Since the nanny in Hangzhou had been accused of stealing and gambling by previous employers, the question that should be asked is how could she be recommended and hired as a live-in caretaker when it was known she had a gambling problem.