Grafting Loquat - Should rootstock and scion be of different lineages?

Hi all,

I have a grafted loquat in my garden, and want to try making a new one by germinating a seed and grafting a branch onto the seedling. I have 2 options for the rootstock:

1) Germinate a seed from the tree in my yard. This means that the rootstock and scion would be closely related. Also, there is only one loquat tree in my yard, and so there was no cross-pollination. This seems to me to suggest limited genetic diversity for the seedling.

2) Germinate a seed from a tree that is growing in a small grove nearby. There are about 4 loquat trees growing together, and hence a good chance of cross-pollination. Also, these trees are not closely related to what will be the scion.

I tend to think the second option would be superior, any thoughts from the community?

Thanks!

My gut reaction is that loquats come tree from seeds like peach/pawpaw and you don't need to graft them unless there is some specific reason

Why do you want to graft the loquat.

Do you want a specific rootstock:
Tree Size: usually to make it dwarfing
Soil Type: acidic vs alkaline vs salty
Rainfall Type: semi-arid 16in vs swampy 60inch
Climate Type: do you want to grow your plant in a zone colder than it is rated for
Pest Management: resistant to specific pest

Why do you want a specific scion
Fruit Shippability: do you need a fruit that doesn't bruise easily, store well during shipping vs get riper, etc
Pest Resistance: Will it handle the pest/humidity conditions that are local to you
Fruit Size/Color: Do you need a very specific size/color fruit
Fruit Taste: similar to above
Pollinator: some folks do a multi-graft to fit a pollinator in a small yard.

We would be able to better help if we knew why you need to graft the plant.

Apparently loquats from seed don't produce fruit true to the parent plant. So, I am grafting to ensure I get the fruit that I want, in this case the "Bessel Brown" variety.