"Threatswatch.org" is a lopsided website whose articled are entirely, if you look, about the victories and just cause of Israelis and Americans and the failures and treacheries of Muslims.
You won't find one single credible news source (Fox, CNN, BBC, anyone) with the dubious, suspect claim that the family on the beach was killed by a land mine.
Morever, if you actually bother to THINK about it, this lie is completely ridiculous. One mine killed SEVEN people? Did they all step on the mine at the same time? Did they happen to step on a mine while having a group hug? Or did they step on seven different mines? And the fact that the Israelis indeed WERE shelling the beach (by their admission) at the same time was just a goofy coincidence?
A former Pentagon analyst who worked in the Balkans (lots of mines there) investigated the scene and concluded it was also a shelling and that calling it a mine is also a stretch.
So:
1. No credible news agencies have reported this "finding," although you will find it on a lot of propagandistic websites.
2. The Israeli government is not pressing this explanation... if it was, you would've seen it on the front page of BBC and CNN as the Israseli government sought to explain that the family's tragic death was not it's own fault. This alibi is so unbelievable that the government is not sharing it with the world, and that is why this "investigation" is showing up on lopsided, right wing propgandistic journals but not respectable news outlets. Not even Fox.
3. The alibi doesn't make any sense. The injuries were compliant with a shelling attack, shrapnel was from Israeli howitzer shells, and to ask us to believe a mine went off and incredibly killed 7 people at the same time while the Israelis were bombing the beach is a long stretch.
It amuses me how eager some people here are to make sure everyone knows "the Palestinians" started it and it's their fault, even so much as to claim Israeli soldiers were kidnapped before the family on the beach was shelled (untrue) and to say that, actually, it was a Palestinian mine that did it.
Rather than being so eager to lay blame for the cause of all this, we should acknowledge that for the most part, there are no clear cut good guys or bad guys in this conflict. Peace, not blame, should be our concern. This conflict is not started by any one party, it's part of a conflict has been raging for over half a century.