So few descendants - why finding DNA matches can be so hard

I n early 2025 I finally found a single descendant of William Buchan born 1801. And late last year the first of a few descendants of Andrew bc1808 were discovered. It had taken over two and a half years. The reason is quite simple - they have so few descendants, especially compared to the fecund numbers of George and Robert. As I am about to go to Scotland, this post describes just how many people are on the family tree and where they live! William Buchan 1801-1965 We are not really sure how many children William had - five or six depending on whether Mary Ann Dickson is his child, or that of his wife's first husband. They did fudge the marriage date to include her birth when she was baptised about 1853. [It is moot concern though since Mary Ann did not marry]. T hree of five children survived to adulthood and all married. George [1851-1905 ] married a woman with a toddler in tow and was nine months pregnant - no matches have been found to either of these two children...