The Collaborative International Dictionary of English v.0.48:

Misbegot \Mis`be*got"\, Misbegotten \Mis`be*got"ten\, p. a.
   1. Unlawfully or irregularly begotten; of bad or disreputable
      origin; pernicious. "Valor misbegot." --Shak.
      [1913 Webster]

   2. Poorly designed or planned; badly carried out;
      ill-conceived.
      [PJC]

WordNet (r) 3.0 (2006):

misbegotten
    adj 1: born out of wedlock; "the dominions of both rulers passed
           away to their spurious or doubtful offspring"-
           E.A.Freeman [syn: bastardly, misbegot, misbegotten,
           spurious]

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "misbegotten":
   bandy, bandy-legged, baroque, baseborn, bastard, bizarre,
   blemished, bloated, bowlegged, cacogenic, club-footed, defaced,
   deformed, disfigured, dwarfed, false, fatherless, flatfooted,
   freak, freakish, gargoylish, grotesque, ill-made, ill-proportioned,
   ill-shaped, illegitimate, knock-kneed, malformed, marred,
   miscreated, misproportioned, misshapen, monstrous, mutilated,
   natural, out of shape, pigeon-toed, pug-nosed, rachitic, rickety,
   rococo, shapeless, simous, snub-nosed, spurious, stumpy,
   supposititious, swaybacked, talipedic, teratic, teratogenic,
   teratoid, truncated, unshapely