Define 'resemble' though. Out of a batch of seedlings some will be whiter than others. Some may have none or little red veining. The shapes and growth habit may be slightly different etc. etc.Some cultivars breed true. Not everything is propagated vegetatively. Take S. leucophylla "Hurricane Creek" for example. It's a strain of leuco with a very white top with little to no visible red veining. These characteristics have become fixed within the population and the seeds from this strain will resemble the parents.