Maria Christina Null was born about 1730. The circumstances of her birth, parentage, and arrival in Pennsylvania have not yet been documented. Some online trees claim she was born in Osnabruck in Lower Saxony in 1720 and that her parents were Anthon Null and Maria Magdalena Brunelle, but there has been no documentary support found for this claim.
She married Matthias Sommer at St. Michael's and Zion Church in Philadelphia in October 1749. The witnesses included Jacob Schütt, Hans Jurg Null, Johann Jurg Kurtz, Philip Haller, and John Dorett. The couple were members of this church from 1750 to 1753, and their two eldest daughters were baptized there. They moved upriver to the Germantown area after 1759, and joined the Rev. Heinrich Melchior Muhlenberg's new St. Peter's Lutheran Church at Barren Hill in Whitemarsh Township north of Germantown. They were members of that church until their 1766 departure, and Matthias was one of its trustees. The Sommers lived near St. Peter’s Church according to Mühlenberg.
The Sommers family were among the original group of German families in Philadephia contracted by John Hughes of Benjamin Franklin & Co. to settle Monckton Township on the Petitcodiac River. Their ship, the single-masted sloop “Lovey” under Captain Nathaniel Shiverick, landed at Hall's Creek in present-day Moncton, New Brunswick on June 3, 1766. Matthias received Lot 7 in the township but died in the early days of the settlement, most likely in 1767.
Christina and the surviving family are mentioned in a March 1768 letter, and she later married widower Jacob Ricker, Jr. and brought her children by Matthias into that household. Their son Andrew remained on the original Moncton grant, while the rest of the family went to Hillsborough Township downriver. Christina died about 1783, in Hillsborough or in Moncton.
Mariah was born in 1734. Mariah Sommer ... She passed away in 1783. 
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It may be possible to confirm family relationships with Christina by comparing test results with other carriers of her mitochondrial DNA.
However, there are no known mtDNA test-takers in her direct maternal line.
It is likely that these autosomal DNA test-takers will share DNA with Christina:
Unknown-294242 and Null-33 appear to represent the same person because: Same person, wife of Mathias Somers/Sommers. Both dates are estimates with no sources for either that I know of. Also, not sure where the Maria can from as the only sources I know of give her name as Christina.