The trouble with such questionnaires is that they generalise too much and do not build in questions which confirm or contradict other questions. This is a science which requires well qualified people to administer the test and then to interpret the results. Sorry to put a damper on it but I have studied this subject.
In answer to the OP, and because I have studied this, I would say it is more likely that life's circumstances determine whether we are generally happy or not. We are all products of our upbringing and how life has treated us.
I am sorry for those who feel sad all the time, there is so much to be cheerful about in our lives when we look at what others have to deal with. I have had such very hard times but do try to find things to be positive about. I think if we try we can usually recognise the good things in our lives.
I need advice for a mutually messy situation
).