D. Donovan, Senior reviewer at Midwest Book Review, wrote this about Umbilical.  It was also featured on her bookshelf of recommended reading in December 2022.

Umbilical opens in modern-day Namibia, where a small chartered plane’s crash involves an undocumented baby and a nun hiding the child.
Thirty years is a long time to percolate the mystery surrounding this event, but it ripples forward to enfold future generations in a surprising manner, and that is one of the hallmarks of strength of Jane Kay’s Umbilical.
Seasoned mystery readers will quickly come to find that Umbilical is not your traditional whodunit. It’s a literary suspense story of actions, consequences, and inheritance that drives a powerful series of interactions and revelations between seemingly disparate characters that are somehow linked by a singular event that cannot be readily explained.
As the ripples through time continue to unfold, readers are treated to a suspenseful story that embraces love, rage, and circumstances which reveal each character’s simmering years of secrets: “Ella breathed fast, anger boiling up from the deep places where she’d stored it for decades. How she detested his entitled authoritarian manner, which made him the only one who was above reproach and everyone else somehow less worthy and therefore fair game for judgements and criticisms purely because they weren’t born the mighty Jack Moore. She felt as if she was about to choke on her anger.”
Kay’s attention to contrasting cultural and social differences as the story unfolds creates an especially thought-provoking milieu. “African sentiments are not Western sentiments…” it is cautioned as special interests and cultural influences clash.
The result is a mystery steeped in Southern Africa which embraces family angst, generations of behaviors and codes of ethics, and choices that lead to attempts to make peace with the past in order to move ahead in the present.
Readers and libraries looking for suspenseful mysteries that supersede genre definitions will find Umbilical as powerful in its story of revelation as it is in its exploration of close-held secrets and answers to ongoing shame and questions.