Conditioning spills over into and is often reinforced by religious beliefs and other customs so that, for example, a Jew, whose religion forbids the eating of pork, might have guilt feeling if he or she ate pork.
红色部分怎么样翻译？词法及语法怎么样理解？
这个句法现象叫 delayed right constituent coordination。即两个结构并列时，由于右端有相同的成分，因而省略了前一个成分。这是语言简洁性的体现。
具体到这句里，事实上并列的是 spills over into religious beliefs and other customs 和 is often reinforced by religious beliefs and other customs 这两个动词短语，其中 into 和 by 的介词宾语相同，因而前者的被省略。
翻译：饮食习惯影响了宗教信仰和其他风俗，同时又（反过来）被这类信仰风俗所强化。
（上面括号里的字是补充性的意译，不是直译。）
再补充一些来自 CaGEL 的这种语法现象的例句：
- She knew of but never mentioned my other work.
- Im interested in but rather apprehensive about their new proposal.
- He ought to, but probably wont, make a public apology.
- She was then, is now, and always will be, devoted to the cause of peace.
当然，就我而言，接触这种现象最多的状况，其实是各种协议条约里的 including but not limited to（包含但不限于）……