Mendel's work was not well known until many years after Darwin published his theory of evolution
Explanation;
-Mendel's work was ignored because it was not widely distributed, and he didn't make an effort to promote himself. In actual fact, the reasons are more complex.
-Gregor Mendel had the answer to Darwin's problem. Traits were not blended, but inherited whole. And according to Mendel's laws of inheritance, a trait that might disappear in one generation might reappear in the following generation. Modern Neo-Darwinism combines both Darwin's and Mendel's work.
50% of their offsprings will have the recessive trait because if you use Punnett square to analyze the data you will see that only 50% of their children will have Tt as their allele