They have been spurred[spur] in part by DNA evidence made available in 1998, which almost certainly proved Thomas Jefferson had fathered at least one child with his slave Sally Hemings
这里的certainly理解为 一定 对吧？most certainly理解为 几乎可以一定？
almost certainly“几乎可以一定”，是非常正确、非常地道的说法。比“可以一定” 的程度是低了一些，为说话人下结论留有空间。有例句为证：
When the final numbers are tallied, sales will almost certainly have fallen.
等到最后的数字统计出来后，几乎可以一定销售额降低了。
《柯林斯高阶英汉双解学习词典》
The bombs are almost certainly part of a much bigger conspiracy
几乎可以一定，这类炸弹是一个更大的阴谋的一部分。
《柯林斯高阶英汉双解学习词典》
It would almost certainly mean the end of NATO
这几乎一定会致使北大西洋公约组织的终结。
《柯林斯高阶英汉双解学习词典》
The arrested man will almost certainly be kept at this police station
几乎可以一定，被逮捕的男子将被扣押在该警察局。
《柯林斯高阶英汉双解学习词典》
This was almost certainly the high-water mark of her career
这几乎一定是她事业的巅峰。
《柯林斯高阶英汉双解学习词典》
