I had a look for you at the RHS page on mistletoe. It seems you just have to sow a selection of seeds as only one in ten germinate and you can't tell which gender they will be. You gather the seeds in spring, which is a bit difficult if you haven't got any...maybe a kind goyer would have some?

You could just use the ones in supermarkets...if you speak to the people putting out the fruit (they seem to be responsible for plants and seasons like Mistletoe) then they may give you berries that fell off and are in the bottom of the box.

Thanks both, does the mistletoe have to be a certain age before the berries appear, I have just read someone saying there plant is 10yrs old and just getting it's first berries.

I suspect your mistletoe is too young to produce berries but it could also be a male...