Not exactly 1,000 years, but more like 120-135,000 years for the male line [1], and 200,000 years for the female line [2].
[1] "Sequencing Y Chromosomes Resolves Discrepancy in Time to Common Ancestor of Males Versus Females " dx.doi.org/10.1126/science.1237619
[2] https://www.princeton.edu/~achaney/tmve/wiki100k/docs/Mitoch...
http://gcbias.org/2013/11/11/how-does-your-number-of-genetic...
After ~15 generations your genealogical ancestors aren't all that likely to have contributed much to your DNA.
Not exactly 1,000 years, but more like 120-135,000 years for the male line [1], and 200,000 years for the female line [2].
[1] "Sequencing Y Chromosomes Resolves Discrepancy in Time to Common Ancestor of Males Versus Females " dx.doi.org/10.1126/science.1237619
[2] https://www.princeton.edu/~achaney/tmve/wiki100k/docs/Mitoch...