Not wanting to offend anyone but the mind is a powerful device...losing a loved one is the hardest thing ever...we all have had that loss...and most of us wish that they were still around...in whatever form.
But the fact remains that in 2015 there has not been to date any conclusive proof via picture or video of anything supernatural....ever...period.
Given that there are more mobile devices on this planet than can capture pictures and video in HD than there are actual people then that stat tends to suggest there is no life after death and there is no supernatural thing...
There are still unexplained situations and coincidences that we haven't yet got the facts to be able to explain but that is not proof of anything supernatural.
Therefore I tend to lean to the fact it is in people's minds...as I say the mind is powerful and our mental faculties are strong.
But life after death? There is no actual evidence or facts to support it which given there have been billions of humans that have died that in itself weighs towards the conclusion I come to.
I of course respect others who disagree.