Jonker was born to No-Maj parents. His father was a successful cabinet maker, which presumably gave him early experience with wood-working, and allowed him to become a skilled wandmaker in his own right. Jonker's wands were in great demand and could be easily identified by the mother-of-pearl inlay they typically contained. Jonker experimented with several different wand cores before settling on hair of the Wampus cat as his preferred kind.
- Pottermore (Mentioned only)