At one time, their values. These. 

JFK was a fantastic man and a staunch Democrat.

Good read here:
[...] The 35th president was an ardent tax-cutter who championed across-the-board, top-to-bottom reductions in personal and corporate tax rates, slashed tariffs to promote free trade, and even spoke out against the “confiscatory” property taxes being levied in too many cities...
https://www.bostonglobe.com/opinion/2013/10/19/would-jfk-never-liberal-still-find-home-democratic-party/ZrxV7lJYHrvWxOjXItAuZJ/story.html
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Listen here:
https://www.youtube.com/watch?feature=player_detailpage&v=I72ZTCO3NOw#t=60
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"John F. Kennedy lowered taxes, opposed abortion, supported gun rights, and believed in a strong military..."

This is a great source of info.

https://www.prageru.com/courses/political-science/jfk-democrat-or-republican