A lot of people seem to be lying about:
Their Age
Their real relationship Status
They personal wellbeing
Etc...
Why they lie:
To get an advantage in a situation
Because they think it is fun, but it is mostly causal with pt.1
They have low selfesteem and need help
They do not fully believe that anyone is honest
Forgot or do not want to use their medication
Spotting the lies of a young child is often very easy, as they do not really have an idea of all the subconcious processes and contradictions they fall prey to when opposed to someone honest.
It is a shame that people depend on lies to achieve what they seem to be wanting.