In pea plants, the trait for being tall (T) is dominant and the trait for being short (t) is recessive. Two heterozygous tall pea plants are crossed. What is the probability of their offspring being tall?

The lineage of pea plants produced round seeds for four generations. the plants that fertilized these pea plants also produced round seeds. however, in the fifth generation, the plant produced to two plants with wrinkled seeds. can that be possible?