Question: Where was the father of Johann Wilhelm, Duke Of Saxe-Jena born?

Maurice Wilhelm, Duke of Saxe-Merseburg
Maurice Wilhelm, Duke of Saxe-Merseburg (5 February 1688 – 21 April 1731) was a duke of Saxe-Merseburg and member of the House of Wettin.
He was born in Merseburg, the fifth (but second surviving) son of Christian II, Duke of Saxe-Merseburg, and Erdmuthe Dorothea of Saxe-Zeitz.
Karl Wilhelm, Duke of Saxe-Meiningen
August Friedrich Karl Wilhelm, Duke of Saxe-Meiningen (Frankfurt, 19 November 1754 – Sonneberg, 21 July 1782), was a duke of Saxe-Meiningen.
Charlotte Marie of Saxe-Jena
Charlotte Marie of Saxe- Jena( 20 December 1669 in Jena – 6 January 1703 in Gräfentonna), was a German princess member of the House of Wettin in the branch of Saxe- Jena and by marriage Duchess of Saxe- Weimar.
She was the fourth child of Bernhard II, Duke of Saxe- Jena by his wife Marie Charlotte, daughter of Henry de La Trémoille, 3rd Duke of Thouars, 2nd Duke of La Tremoille, and Prince of Talmond and Taranto.
The early death of her two brothers and older sister before her own birth left Charlotte Marie as the only child of her parents for several years, until the birth of her younger brother and future 2nd Duke of Saxe- Jena, Johann Wilhelm in 1675.
Friedrich Wilhelm, Duke of Saxe-Meiningen
Friedrich Wilhelm, Duke of Saxe- Meiningen( 16 February 1679 in Ichtershausen – 10 March 1746 in Meiningen), was a duke of Saxe- Meiningen.
John George II, Duke of Saxe-Eisenach
Johann Georg II, Duke of Saxe- Eisenach( Friedewald, 24 July
1665 – Eisenach, 10 November 1698), was a duke of Saxe- Eisenach.
He was the second son of Johann Georg I, Duke of Saxe- Eisenach and Johannetta of Sayn- Wittgenstein.
The death of his older brother, Frederick August—who was killed in battle in 1684 — make him the new heir of the duchy of Saxe- Eisenach.
Two years later( 1686), Johann Georg succeeded his father when he died.
In Kirchheim unter Teck on 20 September 1688 Johann Georg married with Sophie Charlotte of Württemberg.
This union was childless.
When his cousin, the young Duke Johann Wilhelm of Saxe- Jena died( 1690) Johann Georg inherited a part of his duchy, because he was compelled to make a divisionary treaty with the Duke Wilhelm Ernst of Saxe- Weimar, his other cousin and brother- in- law of the late duke.
Johann Georg died suddenly of smallpox, and was succeeded by his brother, Johann Wilhelm.
Christian, Duke of Saxe-Weissenfels
Christian, Duke of Saxe- Weissenfels( 23 February 1682 in Weissenfels – 28 June 1736 in Sangerhausen), was a duke of Saxe- Weissenfels- Querfurt and member of the House of Wettin.
He was the sixth( but second surviving) son of Johann Adolf I, Duke of Saxe- Weissenfels, and Johanna Magdalena of Saxe- Altenburg.
Friedrich Wilhelm I, Duke of Saxe-Weimar
Friedrich Wilhelm I( 25 April 1562 in Weimar – 7 July 1602 in Weimar) was a duke of Saxe- Weimar.
He was the eldest son of Johann Wilhelm, Duke of Saxe- Weimar and Dorothea Susanne of Simmern.
Bernhard II, Duke of Saxe-Jena
Bernhard II, Duke of Saxe-Jena (Weimar, 14 October 1638 – Jena, 3 May 1678), was duke of Saxe-Jena.
He was the seventh child but fourth surviving son of Wilhelm, Duke of Saxe-Weimar and Eleonore Dorothea of Anhalt-Dessau.
Bernhard attended the University of Jena from February 1654 until November 1657.
Subsequently, he was pulled into political affairs when his father sent him to Paris in order to strengthen the relations of Ernestine line with the King Louis XIV, hopefully through a marriage.
The French king, however, made him wait eighteen months for an audience.
The stay in France finally led to his marriage to Marie Charlotte de la Trémoille, daughter of Henri de La Trémoille and Marie de La Tour d'Auvergne.
Her family were residents of the French court where they bore the rank of "princes étrangers".
The wedding took place in Paris on 10 June 1662.
Shortly after, the couple moved to Jena, where their five children were born:
In 1662 Bernhard and his brothers divided the paternal inheritance, and he received Jena.
The marriage of Bernhard and Marie Charlotte was totally unhappy, and, were they seemingly irreconcilable, the duke had decided to marry one of the ladies of his court, Marie Elisabeth of .
He solemnly promised that he would divorce his wife and marry her, and she ceded to his advances.
They had one daughter:
Meanwhile, Bernhard's efforts to have his marriage annulled were unsuccessful, as no theologian or jurist could give him grounds for divorce; and he appeared to reconcile himself with Marie Charlotte.
Nevertheless, on 20 October 1672 he promised in writing to his mistress that he would never forget her, but would care and protect her as if she were his true wife, and giving her the style of "Lady of Alstädt" and an annual rent of 1000 Taler.
Then, in 1674, they were married by a former Jesuit priest named Andreas Wigand, converted to Lutheranism in 1671.
Thus, Bernhard became one of the few cases of bigamy among princes.
The contract declared the children to be legitimate and noble, until such time as an Imperial Act could bring them to a higher rank.
She was given as "Morgengabe" a sum of 20,000 Taler and assigned the Schloss Dornburg as her residence.
She was obliged to keep the marriage secret until the death of the duke's first wife; should she reveal it
, the duke would cease to be bound by the contract.
On 8 November 1676
Marie Elisabeth was raised by the Emperor to the rank of an Imperial Countess ("Reichgräfin"), along with her daughter, and any other legitimate children of hers, with the title of Countess of Altstädt ("Gräfin von Altstädt") and the style of hoch- und wohlgebohrne.
When Bernhard died, was succeeded by his only surviving son Johann Wilhelm, born of his first wife after their reconciliation in 1675.
Marie Elisabeth obtained her "Morgengabe", not without some difficulty.
She survived her "husband" thirty-eight years.
Johann Wilhelm, Duke of Saxe-Jena
Johann Wilhelm, Duke of Saxe-Jena (Jena, 28 March 1675 – Jena, 4 November 1690), was a duke of Saxe-Jena.
He was the youngest but sole surviving son of Bernhard II, Duke of Saxe-Jena by his wife Marie Charlotte, daughter of Henry de La Trémoille, 3rd Duke of Thouars, 2nd Duke of La Tremoille, and Prince of Talmond and Taranto.
William, Duke of Saxe-Weimar
Wilhelm, Duke of Saxe-Weimar (Altenburg, 11 April 1598 – Weimar, 17 May 1662), was a duke of Saxe-Weimar.
Wilhelm was the fifth (but third surviving) son of Johann, Duke of Saxe-Weimar, and Dorothea Maria of Anhalt.
He was brother to Bernard of Saxe-Weimar, a successful Protestant general in the Thirty Years' War, and to Ernest I, Duke of Saxe-Gotha (later Altenburg), a successful and well regarded ruler known as "The Pious".

Answer: Weimar