Most hostas cross-pollinate relatively easily, although some are sterile and others are reluctant to set seed. A list of these types can be found on this site http://www.hostalists.org/hosta_list_sterh.php
The mother plant is referred to as the pod parent & the father plant as the pollen parent
The vast majority of seedlings from plain or variegated pod parents will also be plain. The seedling’s leaf colour will usually be the same colour as its pod parent’s (or the leaf centre if the pod parent has a variegated leaf) but, depending upon its ancestor’s genetics, it may be a different colour. Less than 1 in 1,000 seedlings from plain or variegated pod parents will be variegated and even fewer will be streaked.
The best way to get variegated seedlings is by using streaked pod parents. The reason for this is as follows : The genes in hostas are relatively unstable compared to most plants. They have 3 layers of cells which can be genetically different. Two of these, L1 & L3 form the visible parts of the leaf, the outer and inner parts respectively. If they are have different genes for colour then they will be variegated. In streaked hostas, these layers are mixed together, a characteristic which is often passed from mother to child, resulting in streaked seedlings. However, in most streaked hostas, the 2 layers are constantly working to separate from each other, which will eventually lead to stable variegated offspring.
A streaked pollen parent won’t produce a variegated seedling any more frequently than a plain leafed pollen parent.
Whereas streaked parents can give rise to 6 types of coloured seedlings (including a significant proportion of streaked seedlings as described above but also plain, medio-variegated etc) misted leafed parents (such as Split Milk) give rise to almost all misted seedlings.
Dominance. As in all genetics, certain genes are dominant over others. So, where two types of genes are present together, the characteristic of one will often prevail. Naturally, this has implications for the selection of characteristics in hybridizing. Some of the dominant genes which have been identified by hybridizers are as follows : (1) Lavender flower colour is dominant over white, (2) flower fragrance is dominant over no fragrance, (3) purple petiole colour appears to be dominant over green and (4) yellow leaf colour appears to be dominant over green