I'm sure everyone is aware that peach "pits" (as they're called here in the U.S.) as well as apricot stones and even apple seeds contain a substance (amygdalin) that, when digested produces small amounts of cyanide. Granted, one would have to eat a truck load of pits to be made ill, but why take the chance (unless you're French, in which case you would joyfully use as many pits as you could find to make various dishes, including amaretto, which uses the interior kernel of the pit (called a noyau).
Anyways…a lot of folks don't like to use commercial pectin, which I don't understand, because it's simply made from apples. I use it with ease on everything and don't have a shelf load of unset jams, jellies and preserves… I'm just saying...