Archivist Constance Potter says genealogy can be addictive: once you start, it is hard to stop.

VOA: special.2010.06.28

And, in fact, once you teach an animal something, if you stop doing the teaching the response goes away and this is known as extinction.

事实上，条件反射形成以后，如果得不到强化,条件反应就会逐渐消失,这就是消退。

耶鲁公开课 - 心理学导论课程节选

But another possibility is once you do something it's kind of hard to stop.

但也有可能是因为,婴儿很难使自己的惯性动作停下来

耶鲁公开课 - 心理学导论课程节选