Is it possible that "Wearing your heart on your sleeve" has Jewish origin?
Solution 1:
Shakespeare (in Othello) appears to have been the first to use "wear ones heart upon one's sleeve."
[Iago]
For when my outward action doth demonstrate
The native act and figure of my heart
In compliment extern, ’tis not long after
But I will wear my heart upon my sleeve
For daws to peck at. I am not what I am.
This may be a variant on "pinning one's [soul, belief] on one's sleeve," suggested by another answer.
Given that the Jews had been expelled from England in 1290, and were not permitted to return (or come out of hiding) until well after Shakespeare's time, it seems unlikely to have Jewish origins.
Solution 2:
It seems that, metaphorically, many things can be 'pinned' to one's sleeve :- the soul, the self, one's faith, virtue itself and Gentility.
So I would think that it is a general idiom and not related, specifically, to the custom which places an item on the sleeve near the heart.
OED-3 (subscription required) :-
e. to pin..on, upon, or to one's sleeve: see pin v.1 4b. Hence †to pin one's sleeve upon (obs.). Also, †to attach, assign, or attribute (something) to a person.
(a) 1585 Abp. E. Sandys Serm. i. 10 How sharply are the Corinthians taken vp by the Apostle, for pinning themselues vpon mens sleeues, saying, I am of Paul, and I of Apollos?
1599 Life Sir T. More in C. Wordsworth Eccl. Biogr. (1853) II. 149 I never intended to pinne my soule to another mans sleeve.
1632 R. Sanderson 12 Serm. 295 We may not..build our faith upon them.., nor pin our belief upon their sleeves.
1684 N. S. tr. R. Simon Crit. Enq. Editions Bible 171 Yet am I not such a one as to pin my sleeve so passionately upon St. Jerome as every where to approve his Errors.
1712 M. Henry Popery in Wks. (1853) II. 342/1 They require men..to pin their faith upon the pope's sleeve.
1831 The Remembrancer 198 Men who pin their faith on the sleeve of their neighbour.
1873 J. G. Holland Arthur Bonnicastle i. 35 I pinned my faith to my father's sleeve, and believed as fully and as far as he did.
(b) c1616 R. C. Times' Whistle (1871) ii. 784 Proud meacocke, make the world no more believe Gentility is pind vpon thy sleeve.
1642 Milton Apol. Smectymnuus in Wks. (1851) III. 289 What of other mens faults I have pinn'd upon his sleeve, let him shew.
1668 H. More Divine Dialogues (1713) ii. xxi. 157 It seems a kind of disparagement, to pin Vertue and Divine Grace upon the sleeves of them that are unwilling to receive it.